collaborator

nouns

someone who assists in a plot
collaborator, confederate, henchman, partner in crime
someone who collaborates with an enemy occupying force
collaborationist, collaborator, quisling
is derived from
collaborate
an associate in an activity or endeavor or sphere of common interest
"the musician and the librettist were collaborators"; "sexual partners"
collaborator, cooperator, pardner, partner
is derived from
collaborate