THESAURUS
fifth columnist
Trojan horse, apostate, backslider, bolter, collaborationist, collaborator, convert, crypto, defector, deserter, fellow traveler, fifth column, fraternizer, mugwump, proselyte, quisling, recidivist, recreant, renegade, renegado, renegate, reversionist, runagate, saboteur, schismatic, seceder, secessionist, security risk, separatist, strikebreaker, subversive, tergiversant, tergiversator, traitor, turnabout, turncoat, turntail, underground