William Robert Farmer was born on November 14, 1952, in Pratt, Kansas, as the second child in his family. His parents were of English and Welsh descent.
Farmer's first job, at the age of 15, involved doing voices, especially those of Western stars like John Wayne or Walter Brennan. He and his friends would sometimes go through fast food drive-thrus and order foods in his character voices. Bill attended the University of Kansas and is a member of the Sigma Chi Fraternity. In college, he found work in radio and TV and then moved on to stand-up comedy as an impressionist until he moved out to Hollywood, where he began voicing Goofy in January 1987. In 1982, while he was still doing stand-up comedy, Farmer worked at a comedy club called the Comedy Corner in Dallas, Texas. He continued to work there until his move to Hollywood in 1986.
His decision to move to California came from a Dallas commercial agent who suggested that, given his talent for voices, he should try his luck in California. He was recently married, but he and his wife talked it over and came to an arrangement. She stayed back in Dallas while he commuted for a year after he got an apartment. Then four months after his moving out to Hollywood, his agent asked him if he could do any Disney characters.
He asserts that voice acting is not about funny voices, but about acting. His mentor was the versatile voice actor Daws Butler, the man behind many of Hanna-Barbera's characters. He taught Farmer that when doing cartoon voices, you're not merely doing a funny voice, you're an actor and the acting is premier and you have to think like the character you're doing.