American motion-picture, stage, and musical star noted for his energy, charisma, and versatility. A popular child star best known for his portrayal of the wholesome, wisecracking title character in the Andy Hardy series of films, the short-statured, puckish performer established himself as a solid character actor as an adult.

Rooney made his first stage appearance at the age of 17 months in his parents' vaudeville act. The young performer sang, danced, and told jokes on the vaudeville circuit until 1924, when his parents separated. He and his mother eventually moved to California, where Rooney made his movie debut as a cigar-smoking midget con man in the silent short Not to Be Trusted (1926). Over the next few years Rooney starred as a tough, cocky kid in a series of comedy shorts based on a popular comic strip. He temporarily took the name of his character—Mickey McGuire—as his own, but he changed his name to Mickey Rooney when the series ended (after more than 50 episodes).

Rooney signed a contract with Metro-Goldwyn-Mayer (MGM) Studios in 1934. That year he also appeared at the Hollywood Bowl in a stage presentation of Shakespeare's A Midsummer Night's Dream, directed by Max Reinhardt, and repeated his much-praised performance as Puck in the screen version (1935) of the production. In 1937 Rooney played Andy Hardy, the teenage son of a small-town judge, in a B-picture called A Family Affair; the idealized Hardy family—and especially the exuberant and good-hearted, albeit sometimes misguided, Andy—proved so popular that MGM featured them in 14 more films over the next nine years. During this period, Rooney also gave a riveting performance as a tough punk reformed by Spencer Tracy in Boys Town (1938) and costarred with Judy Garland in a successful series of breezy musicals, including Babes in Arms (1939), Strike Up the Band (1940), Babes on Broadway (1941), and Girl Crazy (1943). Seemingly blessed with an endless supply of energy and talent, Rooney was one of the top 10 box office stars from 1938 to 1943, heading the list in 1939, 1940, and 1941. He was awarded a special juvenile Oscar in 1938.

After he served in World War II, Rooney's star power decreased and his career slackened as audiences preferred the juvenile Rooney to the grown-up one. Although he would never regain the popularity he had as a young star, Rooney earned a reputation as a fine character actor in such roles as the notorious gangster in Baby Face Nelson (1957), the trainer of a washed-up boxer in Requiem for a Heavyweight (1962), a former jockey in The Black Stallion (1979), and a mentally handicapped man in the television movie Bill (1981). He received an honorary Academy Award for lifetime achievement at the 1982 awards ceremony.

Rooney made his Broadway debut in 1979 in the successful Sugar Babies, a nostalgic tribute to burlesque, and continued to perform in popular musical theatre productions, appearing in the title role of The Wizard of Oz in 1998.

His eight wives included the actresses Ava Gardner and Martha Vickers. He published two autobiographies, I. E.: An Autobiography (1965) and Life Is Too Short (1991), and a mystery novel, The Search for Sonny Skies (1994).