In 2006, Clifton was nominated for an Emmy for Outstanding Supporting Actor in a Miniseries or a Movie for Thief.
Clifton has been nominated for two SAG Awards. In 2001, he won Outstanding Performance by the Cast of a Theatrical Motion Picture for Traffic. In 2006, he was nominated for Outstanding Performance by a Cast in a Motion Picture for Capote.
His sister is the actress Veronica Collins.
Clifton's height is 5'8" (1.73m).