As a director, Keenan staged works at the Old Globe Theatre, The Pasadena Playhouse, the Asolo State Theatre, Occidental College, and L.A.'s Tiffany Theater.
Made appearances on three Star Trek franchises: TNG (as Maturin), DS 9 (as Patrick) and Voyager (as King Hrothgar).
Faculty member at USC's School of Dramatic Arts. He directed plays there from 1987 to 2015.