fill-in
1. [ noun ] someone who takes the place of another (as when things get dangerous or difficult)
Synonyms: relief substitute backup backup_man reliever stand-in
Examples:

"the star had a stand-in for dangerous scenes" "we need extra employees for summer fill-ins"

Related terms: peer surrogate locum_tenens double substitute
Similar spelling:   Fillion
  fill_in
  file_in
  film
  filum
  filmy