In gen., he who does any thing, a doer or performer (cf. ago, II.). In gen. of every kind of action: ut illum efficeret oratorem verborum actoremque rerum, Cic. de Or. 3, 15, 57 (a translation of the Homer. πρηκτῆρα ἔργων, Il. 9, 443): Cato dux, auctor, actor rerum illarum fuit, id. Sest. 28 fin.; so Caes. B. C. 1, 26; Nep. Att. 3, 2 al.
In judicial lang., one who brings an action, a plaintiff: accusatorem pro omni actore et petitore appello, Cic. Part. 32; esp. of lawyers: Moloni Rhodio et actori summo causarum et magistro, id. Brut. 89 fin.; so Hor. A. P. 369 al.—Also, one who conducts a suit, an advocate, Cic. Caec. 1.—Hence, At a later period, an agent or attorney; in gen., an administrator or manager or steward, overseer of property or an estate.—So in Tac.: actor publicus, he who administers the public property, Ann. 2, 30; 3, 67: actor summarum, a keeper of accounts or cashier, Suet. Dom. 11, and so often in the Dig.: sub actoribus, overseers (of a household), Vulg. Gal. 4, 2.
In rhetor. lang., one who delivers any oral discourse; and esp. one who delivers an oration, an orator: inventor, compositor, actor, Cic. Or. 19.
A player, an actor: actores secundarum et tertiarum partium, Cic. Div. in Caecil. 15; so id. de Or. 1, 26; id. Q. Fr. 1, 1, 16 (cf. ago, II., and actio, II. C.).