A supporting actor is an actor who performs a role in a play or film below that of the leading actor(s), and above that of a bit part. In recognition of important nature of this work, the theater and film industries give separate awards to the best supporting actors and actresses.
These range from minor roles to principal players and are often pivotal or vital to the story as in a best friend, love interest, sidekick (such as Robin in the Batman series), or antagonist (such as the villain). They are sometimes but not necessarily character roles. In earlier times, these could often be ethnic stereotypes. A supporting actor should usually not upstage the main actor or actress, but often do. The title of the role is usually specific to the performance; that is, a person may be a supporting actor in one film and the lead in another.
In television, the term day player is used to refer to most performers with supporting speaking roles hired daily without long-term contracts.