Full credit if you only named Marvin, since it can be argued that March's Jeckyll/Hyde was the same character and Olivier's secondary role as the voice of the Ghost was uncredited.

Some references inexplicably credit the Ghost in Olivier's film as being performed by John Gielgud, but in fact Olivier disliked working with Gielgud and turned down his request to play the chorus in Olivier's film of Henry V (1946). Gielgud did play the Ghost in his 1964 Broadway production starring Richard Burton, the 1970 Hallmark Hall of Fame television production starring Richard Chamberlain, and in Kenneth Branagh's 1994 radio production; but Olivier played the Ghost in his film by recording the dialogue himself and playing it back at a reduced speed. Gielgud and Olivier worked together directly only five times in their careers:

• In 1934, Olivier took over for Ralph Richardson at short notice in the Gielgud-directed play Queen of Scots.
• In 1936, they alternated the roles of Romeo and Mercutio in the legendary 1936 stage production of Romeo & Juliet directed by Gielgud. This production started Olivier's career as a classical actor, although he never credited Gielgud publicly for the break.
• Gielgud directed Olivier and Vivien Leigh in a troublesome production of Twelfth Night at Stratford, although Olivier was said to have ignored Gielgud's direction.
• Gielgud played Clarence in Olivier's memorable 1956 film of Richard III, although he complained that his role was reduced significantly after its initial release.
• Gielgud and Olivier shared the screen with Ralph Richardson for the only time in Tony Palmer's television film of Wagner.

The only actor to be nominated for playing three roles in a single film is Peter Sellers for Dr. Strangelove: or How I Learned to Stop Worrying and Love the Bomb.