American composer, singer-songwriter, director, and actor. He is perhaps best known for popular songs performed by a number of acts in the 1970s including Three Dog Night's "An Old Fashioned Love Song", Helen Reddy's "You and Me Against the World", David Bowie's "Fill Your Heart", and the Carpenters' "We've Only Just Begun" and "Rainy Days and Mondays", as well as his contributions to films, such as writing the lyrics to "Evergreen", the love theme from A Star Is Born, starring Barbra Streisand, for which he won an Academy Award for Best Song; and "Rainbow Connection" from The Muppet Movie. He also composed the enormously popular opening theme for "The Love Boat" television series, originally performed by Jack Jones, and later, by Dionne Warwick.

He has also had a variety of high-profile acting roles such as Little Enos Burdette in the highly successful 1977 action-comedy Smokey and the Bandit, and as the villainous Swan in Brian De Palma's Phantom of the Paradise (which Williams also co-scored, receiving an Oscar nomination in the process), as well as television, theater, and voice-over work for animation.