walk-on

US /ˈwɑːk.ɑːn/
UK /ˈwɑːk.ɑːn/
"walk-on" picture
1.

a small part in a play or film, with no speaking lines

:
She had a brief walk-on role in the new movie.
He started his acting career with a few walk-on parts.
2.

a person who joins a sports team without having been specially recruited or given a scholarship

:
He made the basketball team as a walk-on.
Many successful athletes started as walk-ons.
1.

denoting a small part in a play or film, with no speaking lines

:
It was a simple walk-on appearance.
The director often uses walk-on actors for crowd scenes.