In The Nightmare Before Christmas movie, the actors play several roles each. Here is the known list:
Danny Elfman -- Jack Skellington, Barrel, Clown
Catherine O'Hara -- Sally, Shock
Paul Ruebens -- Lock
William Hickey -- Dr. Finkelstein
Randy Crenshaw -- Behemoth, Mr. Hyde, Vampire
Carmen Twillie -- Creature Under the Bed, Undersea Gal
Kerry Katz -- Corpse Dad, Creature Under the Stairs, Vampire
Greg Proops -- Harlequin Demon
Serwood Ball -- Mummy Boy
Susan McBride -- Big Witch
L. Peter Callender -- Accordion Player