Already over 30 years old, Hackman decided to become an actor, and joined the Pasadena Playhouse in California. It was in that school that Hackman forged a friendship with another aspiring actor, Dustin Hoffman. Already seen as outsiders by their classmates, Hackman and Hoffman were later voted "The Least Likely To Succeed". Determined to prove them wrong, Hackman hopped on a bus bound for New York City with his wife. Hoffman later followed them. A 2004 article in Vanity Fair described how Hackman, Hoffman and Robert Duvall were all struggling actors and close friends while living in New York City in the 1960s. Hackman was working as a doorman when he ran into an instructor whom he had despised at the Beverly Hills Playhouse. Reinforcing "The Least Likely To Succeed" vote, the man had said "See Hackman, I told you you wouldn't amount to anything." (Some reports allege that it was one of his former drill instructors from the Marines who saw him there and told him this.)
Hackman began performing in several off-Broadway plays. Finally, in 1964, he had the offer to play on Broadway, which opened the doors to the movies. His first role was in Lilith, with Warren Beatty in the leading role. Another secondary role, Buck Barrow, in 1967's Bonnie and Clyde, earned him an Academy Award nomination as Best Supporting Actor. In 1971, he was again nominated for the same award, this time for I Never Sang for My Father, working alongside Melvyn Douglas and Estelle Parsons. The next year he won the Best Actor award for his memorable performance as Popeye Doyle in The French Connection. He also gave us a great interpretation such as Harry Caul in The Conversation (1974), the classic movie directed by Francis Ford Coppola, and appeared in the star studded war film A Bridge Too Far (1977), and showed a talent for both comedy and the "slow burn" as Lex Luthor in Superman: The Movie (1978), and Superman II (1980).
By the end of the 1980s, Hackman was a well respected actor and alternated between leading and supporting roles, earning another Best Actor nomination for Mississippi Burning, and appearing in such films as Hoosiers, Loose Cannons and Bat*21. In 1990, he underwent heart surgery, which kept him away from work for a while. In 1992, he played violent sheriff Bill Daggett in Unforgiven, which earned him a second Oscar, this time for Best Supporting Actor.
Together with undersea archaeologist Daniel Lenihan, Hackman also wrote two novels: Wake of the Perdido Star (1999) and Justice for None (2004).
His distinctive voice can be heard in television commercials from time-to-time, notably for United Airlines, GTE, CNN, and more recently for Oppenheimer Funds and Lowe's Home Improvement.