Brian Keith was born Robert Alba Keith in Bayonne, New Jersey, on November 14, 1921, to actor Robert Keith and stage actress Helena Shipman, a native of Aberdeen, Washington. Some sources also list his full name as Brian Robert Keith. He was raised Roman Catholic. His parents divorced, and he moved to Hollywood and started his acting career at the age of two. He made his acting debut in the silent film Pied Piper Malone (1924) at the age of three. His mother continued to perform on stage and radio, while Robert’s grandmother Apker helped to raise him on Long Island, New York, just 37 miles east of where he was born. She taught young Brian to read books over his age level. Prior to learning to read, he spent a lot of time backstage while his parents performed, being quiet for hours. Helena fondly recalled keeping little Brian in the dressing room in one of her dressing room drawers. He remained calm and was quiet and would sleep through the entire show. From 1927 through 1929, Keith’s stepmother was Peg Entwistle, a well-known Broadway actress who committed suicide by jumping from the “H” of the famous Hollywood Sign in 1932. After graduation from East Rockaway High School in 1939, in East Rockaway, New York, he joined the United States Marine Corps (1942–1945). He served during World War II as an air gunner (he was a radio-gunner in the rear cockpit of a two-man Douglas SBD Dauntless dive bomber in a U.S. Marine squadron), and received an Air Medal.

After the war, Keith became a stage actor, branching out into films and then television. In 1952, he made his debut on three episodes of Tales of Tomorrow, which led him to other roles in shows such as Police Story, a 1950s anthology show, Eye Witness, The United States Steel Hour, Robert Montgomery Presents, The Motorola Television Hour, Campbell Playhouse, The Pepsi-Cola Playhouse, The Elgin Hour, The Adventures of Ellery Queen, and Jane Wyman Presents: The Fireside Theatre. In 1955, Keith starred in his own series, Crusader, as the fictional journalist Matt Anders, who tries to free captive peoples from communist countries. During the 1950s and 1960s, Keith also had guest roles on The Ford Television Theatre, Wire Service, Alfred Hitchcock Presents, Climax!, Zane Grey Theater, Rawhide, Laramie, The Untouchables, The Americans, Outlaws, The Virginian, The Fugitive, two episodes of Wagon Train, and five episodes of 77 Sunset Strip, among many others. In 1960, he won acclaim for his starring role in Sam Peckinpah’s extremely hard-bitten, adult, and short-lived series The Westerner (1960). The following year, Keith appeared as the father of twins in the 1961 film The Parent Trap, costarring Hayley Mills and Maureen O’Hara. In 1966, Keith costarred with Steve McQueen as traveling gunsmith Jonas Cord in the western Nevada Smith. In 1968, as widower Jake Iverson, he costarred with Doris Day in the comedy, With Six You Get Eggroll.

In 1966, Keith landed the role of Uncle Bill Davis on CBS’s popular television situation comedy Family Affair. This role earned him three Emmy Award nominations for Best Actor in a Comedy Series. The show made him a household name. It was in the vein of such successful 1960s and 1970s sitcoms that dealt with widowhood and/or many single-parent issues as: The Andy Griffith Show, My Three Sons, The Beverly Hillbillies, Petticoat Junction, Here’s Lucy, Julia, The Courtship of Eddie’s Father, The Brady Bunch, The Partridge Family, and Sanford And Son. During its first season in 1966, the show was an immediate hit, ranking #15 in the Nielsen ratings. By the end of its fifth season in 1971, Family Affair still had high ratings, but was canceled after 138 episodes. Kathy Garver said about her on- and off-screen relationship with Brian Keith, “‘I’m a cultural Irishman, don’t you know, I’m a cultural Irishman,’ but he went through many manifestations and changes of character, during the five years that we shot. At first, he was up and then his second year, he was going through a divorce and then, the third year, he met somebody else; and he became more anecdotal and told stories that he loved kids, and he was very outspoken about those that he did not like. So, he was a very interesting character and it was Brian and Sebastian Cabot [who played Mr. French] had such a different style of acting and that’s another reason I think that Family Affair was so popular and stayed as it did. Both excellent actors, both coming from very different methods and styles of acting with Sebastian was more from the classical style and he would take home his script and he would dutifully look at every single word and have it to perfection, and then Brian would come in and say, ‘Oh what do we have today? Let me see the scene, uh-huh, uh-huh, let’s go!’ So he was very improvisational, motion of the moment. And those two different styles really worked out each other, very well.”

During the latter part of his life, Keith suffered from emphysema and lung cancer despite having quit smoking 10 years earlier (he appeared in an endorsement campaign for Camel cigarettes in 1955). On June 24, 1997, he was found dead of a self-inflicted gunshot wound in his home at 23449 Malibu Colony Road in Malibu, California, two months after his daughter Daisy committed suicide. It was also reported that he had financial problems and suffered from depression throughout his final days. Maureen O’Hara stated in an interview not long after Keith died, that she emphatically believed he did not commit suicide. She stated that he had a large gun collection and enjoyed cleaning them and showing them to people. She believes he might have been cleaning the gun or looking at it when it went off and was an accident and definitely not a suicide. She had just visited with him and said he was fine and in good spirits. Also, she stated he would not have committed suicide due to his Catholic beliefs. Keith’s family was joined by many mourners at a private funeral, including Family Affair costars Johnny Whitaker and Kathy Garver, and Hardcastle and McCormick costar Daniel Hugh Kelly. He was interred next to his daughter Daisy at Westwood Village Memorial Park Cemetery in Los Angeles, California. On June 26, 2008, Brian Keith received a star on the Hollywood Walk of Fame.