O'Neill, a native of Youngstown, Ohio, became intrigued with acting when he was teaching sixth grade and taking theater classes at Youngstown State University in his spare time.

Seven years later, O'Neill decided to pursue acting as a profession, so he moved to New York and got a job as a bus boy. His first break came when he was understudying the lead in the Broadway play "Knockout." True to theatrical legend, the lead left the show, the understudy took over the role and the rest is history.

His other stage credits include appearances off-Broadway and in regional productions of "The Front Page," "A Street Car Named Desire" and "Of Mice and Men."