tattler

a person who provides information about another's wrongdoing as the office's resident tattler, she can be counted on to report any unauthorized use of the photocopiers Synonyms betrayer, canary [slang], deep throat, fink, informant, nark [British], rat, rat fink, snitch, snitcher, squealer, stoolie, stool pigeon, talebearer, informer, tattletale, telltale, whistle-blowerRelated Words collaborator; blabber, blabbermouth, gossip, gossiper, leaker; snoop, snooper, spy; notifier