back-stabber

Judas betrayer collaborator defector deserter double-crosser double-dealer sympathizer turncoat two-timer

colluder snake in the grass

conspirator deserter hypocrite impostor informer renegade spy turncoat

Judas apostate backslider betrayer deceiver defector double-crosser fink intriguer miscreant quisling rebel snake sneak snitch snitcher squealer tattletale traducer treasonist two-timer whistle-blower wolf

Benedict Arnold stool pigeon

loyalist

defector informer

Judas apostate betrayer conspirator deceiver deserter double-crosser fink quisling rat rebel renegade snake sneak snitch spy squealer tattletale tergiversator treasonist two-timer whistle-blower

Benedict Arnold stool pigeon

adherent