What do you call a walk on actor or extra in crowd scene?

There are a few terms you can use to describe a walk-on actor or extra in a crowd scene:

Formal:

* Extra: This is the most common and general term.

* Background actor: This emphasizes their role in creating the background of a scene.

* Supporting artist: This term is often used in the UK and emphasizes the artistic contribution of even small roles.

Informal:

* Walk-on: This term implies a very brief appearance.

* Crowd performer: This emphasizes their contribution to the crowd's performance.

The best term to use depends on the context and the specific situation.