Stewie is a one-year-old prodigy who has a very sophisticated psyche and is able to speak fluently in an upper class English accent. He reaches his first birthday in the season 1 episode "Chitty Chitty Death Bang", and has not been referred to as being more than a year old since, despite being seen in several episodes attending pre-school. Highly literate and able to cite pop culture references that long predate his birth, Stewie is also entranced by Raffi and the Teletubbies. Stewie succumbs to other childish tendencies – he believes Peter has truly disappeared in a game of Peekaboo; talks to his teddy bear, Rupert, as if he were alive; is overcome with laughter when Lois blows on his stomach; and has no idea how to use a toilet. Stewie also has an extreme dislike for Matthew McConaughey. MacFarlane has stated that Stewie is meant to represent the general helplessness of an infant through the eyes of an adult. Per cartoon physics, his ability to move objects of greater weight than himself is not surprising to other characters, nor is his ability to retrieve firearms from hammerspace, neither is his ability to talk.
Stewie's mastery of physics and mechanical engineering are at a level of science fiction. He has constructed advanced fighter-jets, mind control devices, a weather control device, a teleportation device, robots, clones, a working Transporter device from Star Trek, time machines, a Multiverse Transporter, a shrinking pod, as well as an assortment of guns including lasers, rocket launchers, and crossbows. Stewie employs these to cope with the stresses of infant life (such as teething pain, and eating broccoli) and to murder his mother, Lois, with mixed success at best depending on the objective. As made clear in the pilot episode, Stewie's matricidal tendencies are a result of Lois constantly (and unwittingly) thwarting his schemes, and so he desires to kill her to carry out his plans without her interference. In other, recent episodes, Stewie engages in other violent or criminal acts, including robbery, aggravated assault, carjacking, loan sharking, forgery, and killing off many minor characters (with a tank, guns, and other assorted weaponry).
Stewie eventually realizes his dreams of matricide and world domination in the sixth season two-part episode "Stewie Kills Lois" and "Lois Kills Stewie". The events are reverted in a deus ex machina ending, where most of the story turns out to be a computer simulation. Because of the rather disastrous ending for himself in the simulation, being shot and killed by Peter, he decides to put aside his plans of matricide and world domination for the time being. However, at the end of the season nine premiere, "And Then There Were Fewer", when Diane Simmons is about to murder Lois for uncovering her murderous revenge scheme, Stewie kills Diane with a sniper rifle stating: "If anyone's going to take that bitch [Lois] down, it's going to be me".
Stewie shows a complete disdain for most people, but does show affection and even rare instances of kindness to his family. Such moments include his support for Meg (whom he traditionally calls "Megan") as when he chided Brian's coke-induced hostility to her ("The Thin White Line"), retracted his joke, "I hate you too, bitch" when Meg said "I hate you all" to the family ("Untitled Griffin Family History"), and wiped her tears during a weepy moment. He generally thinks of Peter as an inferior - regarding him simply as "the fat man" and, at one point, harboring doubts that Peter could possibly be his father ("Stewie Griffin: The Untold Story")- but does bond with him over a shared love of practical jokes made at Lois' expense. While Stewie generally regards Chris as a stooge, he has encouraged him, and even helped Chris to dress when he felt too shy to date ("Extra Large Medium") and assists him in dealing with bullies ("Secondhand Spoke"). In a few episodes, such as "Stewie Loves Lois", it's shown that Stewie can love his mother. In that episode, after Lois recovers and repairs a lost Rupert and serves Stewie a meal he likes, he rethinks Lois and accepts her as a loving mother. When he becomes too dependent on her, she deliberately takes no notice of him; when he hurts himself, she tries to show notice of him again, he returns to hating her.
In the more recent seasons, Stewie has a larger amount of freedom from his parents, usually spending much of his time with Brian. This extends to the point of him being able to keep pigs from parallel universes ("Road to the Multiverse") or take part in the television series Jolly Farm ("Go Stewie Go"), as compared to the first season, in which his plans were constantly hindered by Lois. In "The Hand That Rocks the Wheelchair", Stewie inadvertently clones an evil twin of himself after trying to increase his evil nature. By the end of the episode, it is suggested that the original Stewie may have been unknowingly killed by Brian (as he cannot tell them apart) and Stewie turns to the camera with glowing yellow eyes (reminiscent of Michael Jackson's "Thriller"). But so far, the Stewie recently seen in "Trading Places", the follow-up episode, he still seems to have his mostly harmless eccentricity, shown when he asks Brian if he wants to trade places with him for fun. Stewie has had a few rare interactions with his apparent pedophile neighbor Herbert. It should be noted that Stewie intensely dislikes him and is one of the few characters fully aware of Herbert's nature, even calling him a pervert to his face. All this does, however, is move Herbert into thinking Stewie as "feisty".
Despite his allegedly sociopathic nature, Stewie does seem to have a tender side. This is particularly evident through the growing close friendship he shares with Brian, the family dog, whom he considers an intellectual peer (albeit with the substantial reservations expressed in Our Idiot Brian) and Brian is the only Griffin family member who understands Stewie's speaking- treating him just like he would to any other human adult on the show while other characters cannot understand what Stewie is saying. Originally, Stewie enjoyed taunting Brian with curt remarks and abuse; but they have developed into best friends. In the "Road to..." episodes, Stewie often goes on adventures with Brian, usually through difficult and sometimes surreal circumstances. These episodes are generally regarded by critics and fans to be the show's best episodes. They are usually at the center of the show's deepest and most sentimental episodes, one example being the episode "Brian & Stewie", where Brian admits to Stewie that he has considered suicide. In that episode, they also admit that they love each other, not as lovers, but as very close family/friends.
Stewie has shown in a number of episodes that he is sexually attracted to Brian. These moments include a scene in the Family Guy DTV film, Stewie Griffin: The Untold Story, where Brian tells Stewie that he is drunk, Stewie responds, "You're sexy." In the episode, "The Former Life of Brian", when Stewie agrees to assist Brian in a magic show Stewie says, "You can split me in half" (quickly correcting it to "Saw me in half"). When Brian and Stewie make a bet in the episode "McStroke", Stewie says they should "Kiss on it" to seal the deal. In "Movin' Out (Brian's Song)", after Brian's girlfriend leaves him and while the room is completely dark Stewie says to Brian, "Just to get back at her, you should have sex with the first person you see. No matter who it is," then he turns on the light while he is in Brian's face smiling. Also, in the episode, "The Tan Aquatic with Steve Zissou", Stewie believes he is dying of cancer and asks Brian to teach him to ballroom dance before he dies; while they dance Stewie whispers, "I love you," as he hugs Brian, to which Brian responds "What?" and Stewie frantically claims he said "Olive juice!" Lastly, in Three Kings (where an adaptation of Stephen King's Misery was produced), Stewie (as Annie Wilkes) claims to have "fondled" Brian (as Paul Sheldon) while he was asleep.
Stewie has made a strong effort to cheer Brian up on a couple of occasions. In "Jerome is the New Black", after Quagmire's rant leaves Brian in tears, Stewie cheers him up by saying he likes him and letting Brian spend the night in his room. Similarly, in "Dog Gone", when Brian sinks into a deep drunken depression upon discovering that humanity, including the Griffin family, has no regard for the lives of animals (including himself). Stewie steals his collar and plants it on a stray dog, proceeding to fake Brian's death by sending it into a liquor store and subsequently torching the store. Upon hearing of Brian's 'death', the other Griffins realize just how much Brian mattered to them and close a friend he is to the family. Seeing this reaction, Brian is uplifted.
In "New Kidney in Town", he dognaps Brian to prevent the pet from giving the dying Peter his kidneys, and tells him, "I won't let you give your life for the fat man," in which Brian responds, "You can live without a dog but you can't live without a father." Stewie cries and embraces Brian, who gets covered with mucus dripping from the baby's nose. In "Yug Ylimaf", Brian (inadvertently) names Stewie. This was after Brian accidentally reverses the flow of time and Stewie is unborn. After correcting his mistake, Brian rushes to the hospital just in time to see Stewie's rebirth. As he arrives he asks "Where's Stewie?", confusing the family. The family then decides to stick with the name Brian mentioned, therefore re-giving Stewie his name.
In "Life of Brian", Stewie is the one who takes Brian's death the hardest, and when the family adopts a new dog named Vinny, he tries to get rid of him, feeling no one could ever replace his best friend. Two episodes later, in "Christmas Guy", Stewie finds a way to go back in time (despite destroying his time machine) and save Brian, parting ways with Vinny. After he had saved Brian, he joyously said, "you're alive my friend", as he hugged him. As he was explaining to Brian what had happened, Stewie said, "that car killed you, and when it did, a little part of me died as well."
Earlier in the series, before the two became good friends, Stewie contemptuously referred to Brian as "Dog". He similarly referred to his mother as "Lois" and Peter as "the fat man" until accepting them as his parents, reverting to this form of address when frustrated or angry.
Stewie's voice is provided by Family Guy creator Seth MacFarlane, who also provides the voices of Brian Griffin, Peter Griffin, and Glenn Quagmire as well as numerous other characters. MacFarlane based Stewie's accent on the voice of English actor Rex Harrison, particularly on Harrison's performance in the 1964 musical drama film My Fair Lady. MacFarlane has also linked Stewie with David Hyde Pierce on more than one occasion, saying he wants Pierce to play Stewie if a live action version of the show would ever be created.
Stewie's head has the shape of a rugby ball. In the episode "Stuck Together, Torn Apart", a cutaway shows Stewie's head to be normally shaped, until he hits it on the ceiling while bouncing on the bed, and it is elongated into the familiar shape. Flashbacks in "Chitty Chitty Death Bang", however, show his head was already shaped like a football when he was born. The comic strip Jimmy Corrigan, the Smartest Kid on Earth also features an infant boy who has a rugby-shaped head with some hairs sticking out of it, talks in a very eloquent manner, fears his mother and constantly comes up with inventions to help him escape from her. The comic strip's creator, Chris Ware, started drawing Jimmy as early as in 1991. About the characters, he remarked, "[The similarities are] a little too coincidental to be simply, well, coincidental." He further stated, "I don't want a book of seven years' worth of my stuff to become available and then be accused of being a rip-off of Family Guy." 20th Century Fox insists that Stewie is an entirely original character. In a 2003 interview, MacFarlane stated he had never seen the comic strip before, but the similarities are "pretty shocking".
Stewie's sexuality, even though he is a one-year-old, is ambiguous. When the writers began to flesh out Stewie's character beyond being a generic supervillain in season two, McFarlane and the writers began to explore the infant's sexuality with a series of one-off gags, which hinted in "Chick Cancer" and "We Love You, Conrad" that Stewie could be gay. One example is in the episode, "Brian and Stewie," where Stewie's cellphone screensaver is of a muscular man. Another is where he has a picture of Chris Noth in his wallet and he expresses his wishes to have sexual relations with Brian's son, Dylan. When he plays with a baby girl, husband and wife living in a little house in the garden, he discovers she has a boyfriend. He then burns the house and kills them, then asks Brian why he couldn't do the same things with a friend he must with women saying, "Why doesn't that exist?," Brian answers, "That does exist, it's called 'being gay.'" Stewie then says, "That's what gay is? Oh yeah, I can totally get into that." In "McStroke" Stewie asks Brian what it is like at Anal Point; Brian explains, "if you imagine it like a parking space, that you think, 'Gosh, there's no way I'm gonna be able to fit in there.' But then you fold in the side-view mirrors and, sure enough, well, look at that." to which Stewie responds, "Well, in that scenario, it sounds like I'd rather be the parking space than the car." It is also shown in "Road to the Multiverse", it shows a part of the multiverse where there are many homosexuals, and Stewie says "Love it." Then Brian says "Hate it." and they leave to another part of the multiverse. In "Something, Something, Something, Dark Side", Stewie (who plays the role of Darth Vader) threatens to "choke" the person in charge of the tractor beam. It turns out this person is a muscular man, whom Stewie does "choke", but not by neck. The muscular man states "I can breathe just fine...You're choking my-," and is interrupted by Stewie who replies, "I know." It is implied that Stewie is "choking" the man's penis as a means of grasping, suggesting homosexual action on his behalf.
On other occasions, such as when Stewie falls in love with a girl, Janet, in "Dammit Janet!", he has been shown to be straight. Also, in "Baby Not On Board" when Stewie is left alone in the Griffin home, he looks at a copy of Chris's Hustler magazine, he sees a picture of a vagina, then has a panic attack and screams before shooting it with a sub-machine gun saying in a shaky voice, "You...can't...hurt...anyone...anymore." In the commentary for Stewie Griffin: The Untold Story, the writers describe how they were going to make Stewie discover he was gay, but decided to scrap this idea in order to retain Stewie's sexual ambiguity for writing purposes. MacFarlane planned for the series' third season to end with Stewie coming out of the closet after a near-death experience. The show's abrupt cancellation caused MacFarlane to abort these plans, and the episode "Queer Is Stewie?" was actually produced, but never shown. Since that point, MacFarlane has opted to have Stewie portrayed as sexually ambiguous, as, in his eyes, the flexibility of Stewie's sexuality allows for much more freedom in terms of writing for the character. MacFarlane later elaborated:
"He originally began as a diabolical villain, but then we delved into the idea of his confused sexuality. We all feel that Stewie is almost certainly gay, and he's in the process of figuring it out for himself. We haven't ever really locked into it because we get a lot of good jokes from both sides, but we treat him oftentimes as if we were writing a gay character."
When asked why he made the decision "to take Stewie from homicidal maniac to gay little song boy?," MacFarlane answered: "It wasn't a conscious decision. Characters evolve in certain ways and we found that doing the take-over-the-world thing every week was getting played out and was starting to feel a little dated. It was weirdly feeling a little '90s and believe me, if we were still doing that, the show would be on its last legs. I only half-jokingly go by the guideline that, if it's something that might possibly ruin the show, it's a story we should probably do."
MacFarlane told Playboy "We had an episode that went all the way to the script phase in which Stewie does come out. It had to do with the harassment he took from other kids at school. He ends up going back in time to prevent a passage in Leviticus from being written: 'Thou shalt not lie with mankind as with womankind. It is an abomination.' But we decided it's better to keep it vague, which makes more sense because he's a one-year-old. Ultimately, Stewie will be gay or a very unhappy repressed heterosexual. It also explains why he's so hellbent on killing his mother, Lois and taking over the world: he has a lot of aggression, which comes from confusion and uncertainty about his orientation."
MacFarlane has been nominated for two awards for voicing Stewie Griffin. In 1999, he won a Primetime Emmy Award in the category Outstanding Voice-Over Performance. In 2006, he received an Annie Award in the Best Voice Acting in an Animated Television, Production category, for his voice work in the episode "Brian the Bachelor". In addition, Wizard magazine rated Stewie the 95th greatest villain of all time. Stewie was also named the best Family Guy character on a list of "Top 25 Family Guy Characters" compiled by IGN. In 2010, Entertainment Weekly placed him 45th on its list of the "Top 100 Characters of the Past Twenty Years." Gay.com ranked Stewie as the fifteenth gayest cartoon character. Hal Boedeker, a critic for The Orlando Sentinel, called Stewie "a brilliant creation". Stewie (and Brian) usually form the center-plot for the show's highest rated and most critically acclaimed episodes, these being the Road to... episodes. In a list of Stewie and Brian's greatest adventures, five of the Road to... episodes occupied the top five places.
Several commentators, including its author Chris Ware, have noticed similarities between the title character of the graphic novel Jimmy Corrigan, the Smartest Kid on Earth (first published in 1995) and Stewie. Ware has remarked, "[The similarities are] a little too coincidental to be simply, well, coincidental." He further stated, "I don't want a book of seven years' worth of my stuff to become available and then be accused of being a rip-off of Family Guy." 20th Century Fox insists that Stewie is an entirely original character. In a 2003 interview, Seth MacFarlane said that he had never seen the comic strip before, described the similarities as "pretty shocking" and said that he could see how Ware would reach that conclusion."
Stewie is one of the show's biggest merchandising icons, and he has been included on Family Guy T-shirts, baseball caps, bumper stickers, cardboard standups, refrigerator magnets, posters, and several other items. Stewie appears in the Family Guy Video Game!, where Stewie discovers Bertram attempting to outdo him in taking over the world. Desperate to stop him, Stewie shrinks himself and makes his way to Bertram's lair within Peter's testicles to discover his plan, destroys his henchman cloning lab, and rescues a kidnapped Rupert from a rocket. He finally confronts Bertram in the park, where Bertram turns himself into a giant. Stewie Griffin: The Untold Story is a DVD movie about Stewie's secret and what can possibly be his future. Stewie is also a playable character (along with Brian) in the show's second video game, Family Guy: Back to the Multiverse, where the pair travel through the multiverse again, in order to defeat Bertram.
Stewie appeared in Bones, eventually revealed to be the result of FBI Special Agent Seeley Booth's (David Boreanaz) brain tumor. Seth MacFarlane wrote all of Stewie's dialog for the episode. The character appeared in a Coca-Cola commercial during Super Bowl XLII, he and Brian appeared in a commercial for Wheat Thins, he presented a musical number at the 59th Primetime Emmy Awards with Brian, and he appeared at the 62nd Primetime Emmy Awards. He was on the Late Show with David Letterman to present "Top Ten Things You Don't Want To Hear From Your Child."
There is much debate over which characters in Family Guy can understand Stewie. In an interview, MacFarlane said that everyone can basically understand him, but they ignore him or just think to themselves "oh how cute" when he talks. However at a recent ComicCon panel (2011), he compares this to Wile E. Coyote in the old Merrie Melodies cartoons. MacFarlane went on to say that Brian always hears Stewie, and more recently so does Chris, but the writers usually strive for Peter, Lois, and Meg not to hear him. Once Stewie leaves the house, the question of who can understand him depends very much on the story. MacFarlane also states that these rules can be broken for the sake of comedy, so this could change from one episode to another. In the 18th minute, of Episode 4 Season 15, Peter apologizes to the family, to which Stewie comments: "Oh that's nice of you to say". Peter replies: "Thank you, Stewie, who I can understand." referring to the ongoing discussion whether or not other family members, than Brian, are able to understand him. However, Peter's response seems to be a part of the episodes offset setting, where everyone is out of character.