(n.) One who takes the leading part in a drama\; hence, one who takes lead in some great scene, enterprise, conflict, or the like.

Maecenas abettor actor admirer advocate aficionado angel antagonist antihero apologist backer bit bit part buff cast champion character cue danseur noble defender dependence diva encourager endorser exponent fan fat part favorer feature attraction feeder first tragedian friend at court headliner heavy heavy lead hero heroine ingenue jeune premier lead lead role leader leading lady leading man leading woman lines lover mainstay maintainer moving spirit paranymph part partisan patron person personage piece prima ballerina prima donna prime mover principal promoter reliance role second seconder sectary side sider singer soubrette sponsor stalwart standard-bearer standby star straight part superstar support supporter supporting character supporting role sustainer sympathizer title role upholder villain votary walk-on walking part well-wisher