An American woman of Chinese descent, Ada is first mentioned in the original Resident Evil (1996) set in the year 1998. A letter written by dying Umbrella Corporation researcher John was addressed to a woman named Ada. There was an Umbrella researcher named Linda during the early development stages of the sequel (a version popularly known as "Resident Evil 1.5"). The character was eventually given the full name Ada Wong in order to provide a connection to the first game. John was infected with the deadly T-virus during an outbreak in the Arklay Laboratory facility; he asks Ada (who had manipulated him to steal Umbrella's secrets for a rival company) to destroy the Spencer Mansion (the first game's setting) and to reveal the incident to the public.
Ada makes her first on-screen appearance in Resident Evil 2 (1998), set several months after the events of the first game. In the game, she is a spy for an unnamed rival company who is sent to recover a sample of the deadly G-virus from Umbrella's lab in the zombie-infested Raccoon City. Ada poses as a bystander who is searching for her missing boyfriend John when she meets Leon S. Kennedy, a rookie police officer trapped in the city. Her secret agenda is exposed, and (depending on which scenario is played) she is seriously wounded by either Annette Birkin or the monster Tyrant T-103 in an attempt to save Leon. She later drops him a rocket launcher to defeat the T-103. An epilogue in Resident Evil 3: Nemesis as well as a fictional documentary in Code: Veronica confirm that Ada survived the ordeal. Her role in Resident Evil 2 is explored in more detail in Resident Evil: The Umbrella Chronicles (2007) and Resident Evil: The Darkside Chronicles (2009). The Umbrella Chronicles shows Ada's escape from Raccoon City, as she fights her way out and grapples onto an Umbrella helicopter as it passes overhead. Ada also appears as an enemy in another Resident Evil 2 spin-off game, the non-canonical Resident Evil: Operation Raccoon City (2012), in which she is also a playable character in its multiplayer "Heroes" mode.
Her next starring role is in Resident Evil 4 (2005) set in the year 2004. Ada assists Leon in his mission to rescue the U.S. president's daughter Ashley Graham from the sinister cult Los Illuminados that is based in a remote area of Spain. However, her true objective is to obtain a sample of the dominant species Plaga parasite developed by the cult. She reports to the villain Albert Wesker who is now in a high position within the rival company. Ada is dispatched for this mission alongside Jack Krauser who distrusts her and believes she is a threat to Wesker. She enlists the help of the researcher Luis Sera who manages to steal a sample but is then killed by the cult's leader Osmund Saddler. Ada is briefly captured and planned to be sacrificed but manages to escape. After meeting Leon, she saves him from Krauser who was ordered by Wesker to eliminate Leon. Ada destroys the cult's battleship and the Plagas-mutated Krauser, and aids Leon in various ways. Eventually, she is taken hostage by Saddler, who uses her as bait to trap Leon. Leon, however, is able to free her, and Ada provides him with a special rocket launcher to destroy a mutated Saddler before escaping with a sample via helicopter. Ada appears in the game's sub-scenario "Assignment: Ada", as well as in the "Mercenaries" mode. In the PlayStation 2, PC, Xbox 360, PlayStation 3 and Wii ports of Resident Evil 4, a new scenario starring Ada was included. Titled "Separate Ways", it depicts the events of the main game from her perspective. The fictional documentary "Ada's Report" describes her involvement with other characters in the story. In her report, it is revealed that she works for a different organization than Wesker's, sending him an inferior strain and stealing the parasite sample for herself instead.
Ada is a playable character in Resident Evil 6 (2012) set in 2012-2013, where she is "a lone spy working in secret". Her campaign, designed to bring the answer to some of the game's mysteries, becomes available after the player finishes the storylines for the main characters Leon, Chris Redfield and Jake Muller. During the course of the game, it is revealed that Ada is a former associate of the rogue National Security Advisor Derek C. Simmons who becomes dangerously obsessed with her. Though she originally worked on her own agenda, she gets caught up in the game's events and is forced to help Leon in his mission to stop Simmons' plans. Initially single-player only, Ada's campaign features the action-oriented gameplay of Resident Evil 4 and Resident Evil 5, combined with stealth elements and puzzles similar to the earlier games in the series. Ada is primarily armed with a crossbow, uses a grapple gun, and is aided by (or "using") Leon and his new partner Helena Harper. The campaign incorporates boss battles against Helena's C-virus infected sister Deborah and the mutated Simmons from Leon's campaign, as well as a boss fight unique to Ada. Ada's sidekick in Resident Evil 6 is a mystery "agent" who does not appear in any of the cinematic scenes, as he was added post-release via a patch to be an optional online multiplayer partner during her campaign. In addition, both Carla-Ada and the real Ada are unlockable playable characters for the game's "Mercenaries" mode.
Added to the mix is Carla Radames, a researcher who became a clone of Ada and was created by Simmons with the C-virus. Carla, who believes she is actually Ada, is the main villain of the game, leading the Neo-Umbrella forces responsible for unleashing C-virus outbreaks and fighting against the Bio-terrorism Security Assessment Alliance (BSAA) forces led by Chris Redfield. She first appears in the Republic of Edonia in Eastern Europe and then in the city of Lanshiang, China. After learning the truth about herself, Carla is driven insane and resolves to infect the entire world. She eventually succeeds in infecting Simmons, but is killed by one of his men. Ada is forced to fight Carla who injects herself with a massive dose of the C-virus. After destroying the resurrected and mutated Carla, and parting ways with Leon, the real Ada destroys Carla's "greatest creation" before it could fully hatch from its cocoon. Ada then receives a phone call from her organization about a new job, which she accepts.
A voice eerily similar to Ada's can be heard in one of the sneak peek trailers for Resident Evil 7: Biohazard, although it is not known if it is her.
In the live-action film Resident Evil: Retribution (2012), Ada Wong is held captive by the Umbrella-controlled Jill Valentine and fights against Jill and Bad Rain, together with Alice. Despite their romantic involvement in the video game series, Li described Ada and Leon Kennedy's relationship in the film as "subtle". In Retribution, Ada is an associate of Wesker and had defected with him from Umbrella to save the remnants of mankind, while Leon is one of their mercenaries. All three of them survive the events of the movie. She was announced to return in the sixth film, tentatively titled Resident Evil: The Final Chapter, but ultimately did not make a reappearance.
The game series' Ada appears in the second computer-animated Resident Evil film, Resident Evil: Damnation (2012) that is set in an Eastern European war zone. Trailers for the film showed Ada introducing herself as a special investigator from the UN counter-bioterrorism agency BSAA. She is revealed to be a spy and thus captured by President Svetlana Belikova of the film's fictitious Eastern Slav Republic. Ada manages to escape and meets up with Leon (who at first briefly fights with her), then survives and flees. She is last seen speaking to an unknown figure, offering him a stolen sample of the Dominant Plaga strains in exchange for the erasure of an arrest warrant that Belikova and the BSAA had put against her.
Ada was featured in the 1998–1999 manhua Shēnghuà Wēijī 2 ("Biohazard 2"). A romantic comedy retelling of the story of Resident Evil 2 centering on Leon, Claire and Ada was released in the Taiwanese two-issue comic Èlíng Gǔbǎo II by Ching Win Publishing Co., Ltd. in 1999. Capcom screenwriters created two Resident Evil 2 radio dramas broadcast on Radio Osaka in early 1999 and later released by publisher Suleputer as two separate CDs with the common title Biohazard 2 Drama Album, including Ikiteita Onna Spy Ada (lit. "Ada, the Female Spy, is Alive"). Set a few days after the events of the game, it deals with Ada's mission to retrieve Sherry Birkin's pendant with the G-virus sample from Umbrella enforcer HUNK. Ada intercepts the delivery of the locket in the village of Loire in France, eliminating HUNK and his men. She survives an accidental T-virus leak, escapes and realizes her feelings for Leon, deciding to quit the spy business and return to him. Canonically, the characters' story arcs are continued differently, as Ada keeps the pendant with the G-virus and resumes her activities as a spy.
Two action figures of Ada were included in the figure sets Resident Evil 2: Platinum Edition 2 by Toy Biz (1998) and Resident Evil 4: Series 1 by NECA (2005). Hot Toys released a 1/6 scale action figure of the character in 2012. Several Ada statuettes were also released exclusively in Japan. Sony Music Entertainment's Biohazard: The Umbrella Chronicles Original Soundtrack features Ada on the covers. In 2011, Ada Wong was added to Bandai's Resident Evil Deck Building Game in the expansion Nightmare. Ada-related items were also released with the pre-order and limited editions of Resident Evil 4. The character made her first guest appearance in the browser-based social game Onimusha Soul (2013), where she was re-designed to fit a feudal Japan theme. Ada also appears as a non-playable character in the tactical role-playing game Project X Zone 2.
When Resident Evil 2 was still in development, Ada was a researcher named Linda who aided the player throughout the game. The character was changed for the game's final version. Her costumes include a red casual miniskirt outfit as seen in Resident Evil 2, her now-iconic red dress and a black combat suit from Resident Evil 4, and an outfit consisting of a red shirt with raised collar, black leather trousers and high-heeled boots from Resident Evil 6. Ada's motion capture actress in 'Resident Evil 6, Michelle Lee, said that the process was "definitely a challenge and with the amazing team they were very specific on how she moved, her specific characteristics and even how she stood still".
Ada is voiced by Sally Cahill in Resident Evil 2, Resident Evil 4 and Resident Evil: The Darkside Chronicles, by an unnamed actress in Resident Evil: The Umbrella Chronicles, and by Courtenay Taylor in Resident Evil: Operation Raccoon City, Resident Evil: Damnation and Resident Evil 6. Cahill described the character as "a totally hip, modern, kick ass femme fatale who could handle weapons awesomely" and stated that she loved Ada's "resilience, her strength with still being sexy and very female". Taylor said: "Obviously, they want the voice you auditioned with, but seeing Ada made me give her characteristics. She's sort of cat-like and she walks very quietly and you can tell she's very lithe. She's sort of effortless, so that was great."
In 2011, Li Bingbing was cast as the Resident Evil live-action film series version of Ada, only a few days after her first audition. She did not know anything about the games and the characters, but after learning about them, she thought that Ada's personality was "very much" like her own. The film's producer Robert Kulzer described her as "perfectly cast", saying: "In addition to being an extremely talented actor, she's sharp, sexy and smart—all qualities that the Ada Wong character had to have." During filming, Li wore a US$7,500 wig and "enjoyed" the firearms training she received. She complained about her being cold in Ada's revealing "qipao with a high slit that flapped when the wind blew", but added, "I wanted the slit to be that high after I saw the images of Ada Wong from the game... Not that I wanted it to be that high but that was where the opening would be the most beautiful and cool." Apparently due to the Senkaku Islands dispute, Li did not attend the Tokyo premiere of the film and reportedly also requested that her image be edited out of its promotional posters in Japan. In the film, Ada's voice was dubbed by Sally Cahill in English and by Maya Okamoto in Japanese.
The character was well received. In 2007, Ada was listed among the 50 greatest female characters in video game history by Rob Wright of Tom's Games, who suggested she be played by Kelly Hu in the live-action Resident Evil series. That same year, Ada was ranked second on the list of top "video game chicks" by ActionTrip, and, together with Leon, she was also included by Alexander Villafania in The Inquirer's 2007 list of the most memorable video game love teams. GameDaily featured her as their "Babe of the Week" in 2007 and described her as a "gun-toting hottie" with capabilities to star in her own video game. In 2011, "a highly disfunctional [sic] relationship" between Ada and Leon was ranked as the ninth top video game romance by James Hawkins of Joystick Division. IGN included Ada on the list of characters they would like to see return for Resident Evil 6. Retribution producer Jeremy Bolt said fans were "very, very pleased with all of our choices [in the film], particularly Li Bingbing, who plays Ada Wong. They visited us on set last week, and they were really blown away by her." According to Li Bingbing speaking in 2012, the character has "a big fan base" in China.
Mass media outlets from around the world have described Ada one of the sexiest Asian and general female characters in all of video gaming. GameTrailers named her a "sexy she-devil" and ranked her number five among the top ten "gamer babes" of 2007. In 2008, UGO ranked Ada as the fourth top "videogame hottie", describing her as "drop dead gorgeous" and stating that they anticipate what the series has in store for her in the future, while Chris Buffa of GameDaily ranked her the 12th "hottest game babe". GameDaily also included her in the Babe of the Week galleries "Asian Beauties" and "Girl Power" where she was listed alongside Claire Redfield, Jill Valentine and Sheva Alomar. In 2009, this "kinda babe guys dream about" was featured in MSN's list of "gaming's hottest babes", as well as showcased in a similar article by Polish tabloid Fakt. In 2010, The Times of India listed her among the nine "sexiest babes" of action games and Sarah Warn of AfterEllen ranked her as the 11th "hottest" female video game character. In 2011, Complex ranked her as 24th "best looking sideline chick in games", commenting on Ada's resemblance to Nikita from La Femme Nikita. In 2012, Complex's Larry Hester ranked her as the eight best Asian character in video games, stating that this "bad girl killed zombies like roaches with the sophistication of a ballet dancing gunslinger," while Larry Hester from the same magazine put her at 28th spot on his list of the "hottest" women in video games, describing her as "enshrined in fanboy canon forever more." Polish web portal Interia.pl also included Ada from Resident Evil 6 among the "sexiest game heroines" of the year. In 2013, ZoominGames ranked Ada as number one top Asian female in gaming for her aura of mystery and combining "cool with sexy", while Scarlet Clearwater of Soletron ranked her as the eight sexiest female video game character. In 2014, she was ranked as the seventh best looking game girl by Brazilian GameHall's Portal Play Game and David Arráez from Spanish newspaper La Nueva España included her among ten sexiest male and female characters in video games, choosing her over Jill due to her Oriental beauty". In 2015, Indonesian television Liputan 6 ranked her as the third most sexy Oriental woman character in games.
Lara Crigger of The Escapist found Ada to be not only "the femme fatale archetype given pixilated form" but also "a strong, feminist role model" that is "beautiful and sexual" in light of the existentialist philosophies of Simone de Beauvoir. According to Nadine Farghaly of the University of Salzburg, unlike the typically "sexless object" characters such as the Resident Evil series' own Claire Redfield and Rebecca Chambers, or Silent Hill's Heather, Ada is in her opinion a positively gender fluid character as "she has attributes typically associated with males, such as physical strength and intelligence, and traits typically associated with females, such as beauty and poise." However, Play editor Gavin Mackenzie criticized her perceived "bitch" personality in Resident Evil 4 in retrospective from the events of Resident Evil 2. Complex ranked Ada 19th on the 2011 list of "most diabolical video game she-villains", noting her "dragon-lady qualities." In 2013, Liz Lanier of Game Informer included Ada among top ten female villains in video games, stating that "whether you want to call her a bad guy or just an anti-hero, it's clear that her enemy is whoever gets in her way; if that happens to be a former ally, so be it." She was also included on the 2014 list of top ten "hottest" female villains in gaming by Travis Huber of Cheat Code Central. Ryan Bates of Game Revolution ranked her as the 16th on his 2014 list of top "mean girls in gaming" and wrote that "the scariest part about this Resident Evil stalwart is that players never know if she's working for the Umbrella Corporation, for Wesker, for someone else altogether, or for her own motives. Ada proves that a person, man or woman, without loyalties is a person to be distrusted." ZoominGames put her at number one spot of their 2014 top list of femme fatales in gaming.
Matt Cundy of GamesRadar found Ada's iconic costume from Resident Evil 4 to be unsuitable for the game's theme, ranking her "out-of-our-price-bracket Shanghai hooker" look as the most impractical of all main outfits of the series' stars and commenting that anyone dressing like her to fight zombies "would have to be certifiably mental." Contrary to his opinion, some film critics expressed a positive opinion about the practicality of Ada's high-slit dress, and Lisa Foiles of The Escapist included Ada (as well as Jill and Sheva) among her five examples of actually practical female hairstyles in video games. Chris Warrington of PlayStation Official Magazine included Ada in her characteristic red dress on the 2012 list of eight best dressed PlayStation characters, calling her "the wearer of the finest dress on the PlayStation." In 2014, Daniel Żelazny from Polish magazine PSX Extreme ranked it as the seventh best female outfit in games, while Julia Cook of Paste chose Ada as "best dressed lady" in gaming and also called her "arguably the sexiest character in videogames."