Donald David Dixon Ronald O'Connor (August 28, 1925 – September 27, 2003) was an American dancer, singer and actor. He came to fame in a series of films in which he co-starred, in succession, with Gloria Jean, Peggy Ryan, and Francis the Talking Mule.

O'Connor was born into a vaudeville family, where he learned to dance, sing, play comedy, and perform slapstick. The most distinctive characteristic of his dancing style was its athleticism, for which he had few rivals. Yet it was his boyish charm that audiences found most engaging, and which remained an appealing aspect of his personality throughout his career. In his Universal musicals of the early 1940s, O'Connor was a wisecracking, fast-talking teenager, much like Mickey Rooney of Metro-Goldwyn-Mayer. But by 1952 and Singin' in the Rain, MGM had cultivated a much more sympathetic sidekick persona for him, and that remained O'Connor's signature image.

His best-known work was his "Make 'Em Laugh" dance routine in Singin' in the Rain (1952), for which O'Connor was awarded a Golden Globe. He also won a Primetime Emmy Award from four nominations and received two stars on the Hollywood Walk of Fame.