One who performs for, or entertains, an audience.
One who performs or does anything.
Such a part in a play or film.
One who arrives and boards transport (such as a train or ferry) without having booked in advance.
A student athlete who wants to try out for a college sports/athletic team without the benefit of a scholarship or having been recruited.
An actor of a small (or "bit") part in a theatrical production or film, often without speaking lines.