CREW. PERFORMERS – Schirmer Encyclopedia of Film

The stars and supporting actors are rarely the only performers in a film. Most films also use extras, who
perform small non-speaking roles, often as part of a
crowd. Many films also require stunt performers to
execute potentially dangerous physical actions, such as
catching fire. Some performers work as doubles, imitating
an actor who is unavailable, and are often filmed in long
shot or from a rear view. Stunt doubles can be used to
create the illusion that an actor is performing his or her
own stunts. Body doubles are used when an actor does
not possess the required physical attributes or when a star
refuses to appear naked. Other performers are not seen
physically but are featured on the soundtrack. They
include voice-over artists, who are used for spoken narration, and voice actors, who create the character voices in
cartoons. Sometimes the voice of a live actor is replaced,
a practice especially common when singing is required.
The Hollywood star Rita Hayworth (1918–1987) had
her ‘‘singing voice’’ recorded by other artists, including
Nan Wynn (1915–1971), Martha Mears (1908–1986),
Anita Ellis (b. 1920), and Jo Ann Greer (d. 2001).
Stand-ins do not appear in the final film, but have a
very important function. During the preparation of a
shot, when lighting is set up and camera movements are
rehearsed, they replace the actors in order to allow the
actors time for other preparations, such as makeup.