If an unfamiliar actor has the lead role, he may be listed last in the list of principal supporting actors, his name prefixed with "and introducing" (as Peter O'Toole was in "Lawrence of Arabia") However "and introducing" is now mostly used in feature films by a young actor (usually a child) who appears for the first time in a motion picture. Sometimes, he may not receive special billing even if his role is crucial. For example, the then-unknown William Warfield, who played Joe and sang "Ol' Man River" in the 1951 film version of "Show Boat", received tenth billing as if he were merely a bit player, while Paul Robeson, an established star who played the same role in the 1936 film version of the musical, received fourth billing in the 1936 film.