Michael Keaton was born Michael John Douglas on September 9, 1951, in Coraopolis, Pennsylvania, a suburb of Pittsburgh, to Leona Douglas, a single mother. He was the youngest of seven children. After graduating from Montour High School in 1969, he studied speech at Kent State University in Ohio. After two years, he dropped out, moved back to his hometown of Pittsburgh, and tried performing stand-up comedy in small local venues. When that was unsuccessful, he joined WQED Radio, Pittsburgh's major public station, on the production staff in 1972. His first major media appearance, on episodes of the children's television show Mister Rogers' Neighborhood, led him to move to Los Angeles to pursue an acting career in 1975. There, he appeared in guest shots on several other popular television programs, including Maude in 1977 and The Mary Tyler Moore Hour in 1979.

After discovering that both a Michael Douglas and a Mike Douglas already existed in the acting world, he changed his name to Michael Keaton, after actress Diane Keaton. He did not know Keaton at the time; he simply liked the sound of the name. After several years touring with Los Angeles's Second City comedy troupe, he got his first big break in the comedy series Working Stiffs with John Belushi in 1979, which established Keaton's comedic talent. Around this time, Keaton met television actress Caroline McWilliams, known for roles in soap operas Guiding Light and Another World, and they were married in 1982. Meanwhile, Keaton made his first movie appearance as Bill Blazejowski in Night Shift in 1982, where a great performance earned him the lead role in major comedy Mr. Mom in 1983. After the birth of his son, Sean Keaton, in 1983, Keaton starred in Johnny Dangerously in 1984 and Gung Ho in 1986.

In 1988, Keaton landed the role of the comical villain Beetlejuice in Tim Burton's hit movie of the same name. His brilliant performance as the morbid comedian earned him a National Society of Film Critics (NSFC) Award for Best Actor. He also made an impression on Burton, and the next year, Burton cast him as the lead in his remake of Batman. Despite fans' protest at the hiring of an actor with a reputation for comedy, Keaton turned the movie into a hit with a spectacular performance, with critics lauding his presence as the darkly obsessive millionaire. Keaton and McWilliams divorced in January 1990, but his film success continued. After performing as a psychotic tenant in 1990's Pacific Heights and a beat cop in One Good Cop in 1991, he again took on the role of the Caped Crusader for 1992 sequel Batman Returns, turning in another great performance. Although this was his last appearance as Batman, Keaton is still considered one of the best actors to play the character.

Since his last picture as Batman, Keaton has continued to enjoy success as an actor, although his movies have been smaller than the major hits of his earlier career. He returned to his original genre of comedy as a burned-out tabloid writer in 1994's The Paper, but after his next film, Speechless, was a flop, he took a year off from the big screen. He returned with Multiplicity in 1996, about a man who has himself cloned to ease his busy workload, following this with a role as a ruthless FBI agent in Jackie Brown in 1997. He also starred in Desperate Measures in the same year, his last major film for several years.

After largely disappearing from the movie scene, Keaton starred in the television movie Live from Baghdad in 2002, getting a Golden Globe nomination for Best Performance by an Actor in a Mini-Series or a Motion Picture Made for Television. A few years later, he tested the water again with small-market film Game 6 in 2005, earning just $100 a day to play a Broadway playwright whose career hangs in the balance. He finally made his full return in the 2005 film White Noise, starring as an architect whose attempts to speak with his dead wife spiral out of control into a paranormal disaster. He also played the protagonist's father in Herbie Fully Loaded in the same year and had a voice role in 2006's animated film Cars.

On April 11, 2006, Keaton returned to his hometown to throw out the first pitch at the Pittsburgh Pirates baseball team's first home game, making headlines afterwards by lashing out in an interview at the organization, which had 13 consecutive losing seasons. "I fear they will take advantage of the goodwill of the people who continue to show up," he said, commenting on the owners' lack of spending on players despite the team's profitability. His statements have gained him the respect of many Pittsburghers who agree with his sentiments.

Keaton currently lives in Santa Monica, California, and appeared in the 2007 television mini-series, "The Company," about the CIA during the Cold War. More recently, Keaton provided the voice of Ken in the popular Pixar film Toy Story 3, while also taking a minor role in the comedy The Other Guys. Fans would be pleased to hear that in 2010, Keaton announced interest in a Beetlejuice sequel.