Mark O'Connor (born August 5, 1961 in Seattle, Washington) is an American classical, bluegrass, jazz and country violinist, fiddler, composer and music teacher. O'Connor's music is wide-ranging and critically acclaimed, and he has received numerous awards for both his playing and his composition. As a teenager he won national string instrument championships for his virtuoso playing of the guitar and mandolin as well as the fiddle. His mentors include Texas old-time fiddler Benny Thomasson who taught O'Connor to fiddle as a teenager, French jazz violinist Stéphane Grappelli with whom O'Connor toured as a teenager, and guitarist Chet Atkins.

O'Connor currently resides in New York City.