Ernest O'Donnell (born November 24, 1968) is an American actor who is known for his roles in various Kevin Smith films, most notably Clerks.

O'Donnell was the best friend of writer/director/actor Kevin Smith in high school. They had a brief falling out after graduation and have been close friends since then. Ernest O'Donnell has appeared in a number of Kevin Smith films. His most notable role is the part of Rick Derris in Clerks, though he was originally intended to play the part of Dante Hicks.