Green’s Dictionary of Slang

(US/Can.) one who distinguishes themselves from a crowd.

1928		Collier’s 29 Dec. 26/2: When the show opened, this girl had improved in her dancing so amazingly that she was a distinct ‘standout’ [DA].
1953		A.J. Liebling Honest Rainmaker (1991) 96: Mr Hearst ranks only just behind [...] Aneurin Bevan in the Colonel’s all-time list of standouts.
a.1964		‘Sugar Hill’ in D. Wepman et al. Life (1976) 93: He had a choice chick named Dolly, a standout among the whores.
1975		Sepe & Telano Cop Team 20: We’d be a stand-out on the street.