Karen Kay Sharpe was born in San Antonio, Texas, in 1934. According to the federal census of 1940, her parents, Howard and Dorothy Sharp (spelled with no "e") were both natives of Indiana. That census also documents that in 1940 the family continued to reside in San Antonio and her father worked then as a sales manager for a local electric company. As a child, Karen studied ballet and theater. In 1952, at the age of 18, she appeared in Stanley Kramer's production of The Sniper, directed by Edward Dmytryk. She spoke three lines in the film while sitting on a drugstore stool and did not personally meet Kramer at that time. That same year, she was cast uncredited as the younger sister of Janice Rule in the film Holiday for Sinners, opposite William Campbell. In 1953, she appeared as Lucy Colfax in the John Payne-Jan Sterling film, The Vanquished.
Director William A. Wellman cast Sharpe in the 1954 airline disaster film The High and the Mighty, which was distributed by Warner Bros. In the film she portrays Nell Buck, a young bride who overcomes her fear of death through passion for her new husband, Milo, played by John Smith. Her performance in The High and the Mighty propelled Sharpe to the 1954 Golden Globe Award for "New Star of the Year". In 1955, she played Stella Atkins in the western film, Man with the Gun.
During the 1959-1960 television season, Sharpe was cast as Laura Thomas, the girlfriend of the title character, in 18 episodes of the CBS western series Johnny Ringo, starring Don Durant as a fictitious gunfighter turned small-town sheriff. Johnny Ringo was the first series produced by Aaron Spelling. In 1961, she appeared in the episode "Never Walk Alone" of ABC's western series Stagecoach West, performing in the role of Ruby Walker. Her other ABC appearances were on 77 Sunset Strip (twice), Hawaiian Eye, Burke's Law, The Pepsi-Cola Playhouse, and The Dakotas.
Later in 1961, seven years after The High and the Mighty, Sharpe was reunited with John Smith in his NBC western series, Laramie. She portrayed Madge Barrington, the daughter of a Colonel John Barrington, played by George Macready, whose character was presumably modeled after John Chivington of the 1864 Sand Creek massacre in Colorado. In the storyline Barrington escapes while facing a court martial at Fort Laramie for his subsequent role in the Wounded Knee Massacre in South Dakota in 1890. The episode reveals that Slim Sherman was present at Wounded Knee and testified against Barrington. Madge takes Slim hostage and presents papers that she contends justify her father's harsh policies against the Indians. Slim manages to escape but is trapped by the Sioux and must negotiate with the Indians to escape massacre.
Sharpe appeared in many other television series in the 1950s and early 1960s, including CBS's Racket Squad, Lux Video Theatre, Playhouse 90, General Electric Theater, The West Point Story, The Millionaire (in the lead role in "The Anitra Dellano Story"), Westinghouse Desilu Playhouse, Perry Mason (the title character in the 1958 episode "The Case of the Hesitant Hostess"), The Smothers Brothers Show, and Gomer Pyle, U.S.M.C.
She appeared twice on the CBS Western Rawhide, in that series' 1962 episode "Gold Fever" and in its 1963 episode "Incident of the Black Ace". She also guest-starred on several other CBS Westerns: Gunsmoke, in the episode "Sweet and Sour"; Trackdown, playing Edith Collins in "The Young Gun"; The Texan, as the character Jessie Martin in "Private Account"; and on Yancy Derringer, performing as Patricia Lee in "Game of Chance". In yet another television genre, she guest-starred as well on David Janssen's contemporary crime drama Richard Diamond, Private Detective in "Echo of Laughter", one of the last episodes of that series broadcast on CBS before it switched to NBC for its final year of production.
Besides Laramie, Sharpe appeared on several other NBC series, including Fireside Theater, Cameo Theatre, Hallmark Hall of Fame, The Ford Television Theatre, Matinee Theater (seven times), The Loretta Young Show, Bonanza, Overland Trail, The Americans, and The Man from U.N.C.L.E. Sharpe appeared twice on NBC's I Dream of Jeannie.
Sharpe was cast in several syndicated television series too, including The Range Rider, Death Valley Days, and the American Civil War drama The Gray Ghost. She appeared on Studio 57, when it was broadcast in 1954 on the former DuMont Television Network. In 1955, she played the role of Clara Bryant Ford in the television film A Story About Henry Ford, based on the automobile mogul, who was portrayed by Arthur Franz. That same year she played Martha Custis Washington in the television film The Courtship of George Washington and Martha Custis, with Marshall Thompson, nine years Sharpe's senior, cast as Washington.
Sharpe's last roles on a regular series were in two episodes of The Wild Wild West. She appeared in Jerry Lewis's 1964 film The Disorderly Orderly, during which time she met Stanley Kramer, who was also directing Ship of Fools on the lot of Paramount Studios. They married on September 1, 1966. She later stopped acting to devote full-time to her family, including the couple's two children, and to serve as assistant to her husband in the film industry.
Sharpe maintains the Stanley Kramer Library. She established the Stanley Kramer Award at the Producer's Guild and the Stanley Kramer Fellowship Award in Directing through the University of California, Los Angeles. Both designations showcase and honor the works of socially conscious young filmmakers.The Sniper, uncredited (1952)
Holiday for Sinners, uncredited (1952)
Strange Fascination (1952)
Army Bound (1952)
Bomba and the Jungle Girl, cited in film series (1952)
The Vanquished (1953)
Mexican Manhunt (1953)
The High and the Mighty (1954)
Mad at the World (1955)
Man with the Gun (1955)
Man in the Vault (1956)
Tarawa Beachhead (1958)
The Disorderly Orderly (1964)
Valley of Mystery, made-for-television movie (1967)