impersonator

burlesquer, caricaturist, lampooner, mocker, parodist, satirist

mime, mimer, mummer, pantomime, pantomimist

actor, entertainer, performer, player, trouper

ape, copycat, echo, parrot, rubber stamp

barnstormer, enactor, entertainer, performer

actress, starlet

lead, leading lady, leading man, star

coactor, costar

extra, spear-carrier, supernumerary, walk-on

monologuist (or monologist)

prima donna, scene-stealer

double, understudy

comedian, farceur

tragedian, tragedienne

ape, aper, ham, imitator, impressionist, masker, masquerader, mime, mimic, pantomime, pantomimist, personator, poser

buffoon, clown, harlequin, stooge, zany