Rooney died of natural causes, according to TMZ, though the Los Angeles County Coroner's office has yet to confirm this.
Rooney's career in show business spanned a mind-boggling nine decades. Born Joe Yule Jr. to vaudevillian parents who routinely incorporated him into their act, Rooney signed to MGM at age 14 and quickly became one of the studio's biggest stars.
Rooney's fame skyrocketed when he portrayed Andy Hardy, of The Hardy Boys series, in 16 films from 1937 to 1958.
He frequently collaborated with friend Judy Garland on films like Love Finds Andy Hardy and the Oscar-nominated Babes in Arms. He also starred with Elizabeth Taylor in National Velvet and Spencer Tracy in Boys Town.
Rooney won multiple awards, including an Emmy, two Golden Globes and an Honorary Oscar, though he was also notorious for his turbulent personal life. The 5-foot-2 movie star married eight women, including actress Ava Gardner.
Rooney is survived by his estranged wife, Jan Chamberlin, who told The Hollywood Reporter that she had not seen her husband since last year.
Chamberlin said that Rooney had been living at her son Mark's house. For a 2011 Congressional investigation into elder abuse, Rooney claimed that Jan's son, Chris Aber, had emotionally and financially exploited him.
He is also survived by nine children.