[1] He may be best known to some audiences as the voice of Officer Charlie Dibble in the Hanna-Barbera TV cartoon series Top Cat (1961–62).

He signed a seven-year contract with Warner Bros. in 1932 and established himself quickly as a gloom-faced, wisecracking character player, useful in comedies, dramas, and musicals (he was an accomplished dancer).

He was a member of Hollywood's so-called "Irish Mafia", a group of Irish-American actors and friends which included Spencer Tracy, James Cagney, Pat O'Brien, and Frank McHugh.

(1956–57), starring Jeannie Carson and often portrayed Muggsy on the 1950s-1970s CBS series The Red Skelton Show.

Eleven days before his death, he made his final appearance, at the end of Billy Wilder's remake of The Front Page (1974); it was released posthumously.