(n.) One who masquerades; a person wearing a mask; one disguised.

Holy Willie Joseph Surface Mawworm Pecksniff Pharisee Tartuffe actor affecter ape attitudinizer bluffer canter canting hypocrite charlatan con man confidence man conformist copier copycat copyist counterfeiter cuckoo deceiver dissembler dissimulator double-dealer echo echoer echoist fair-weather friend faker false friend flimflam man flimflammer forger formalist fraud humbug imitator impersonator imposter impostor liar lip server lip worshiper masquerader mealymouth mime mimer mimic mimicker mocker mockingbird monkey mountebank parrot pharisee phony pietist pious fraud plagiarist poll-parrot polly polly-parrot poser poseur pretender quack ranter religionist religious hypocrite sanctimonious fraud sham sheep simulator sniveler snuffler spiritual humbug summer soldier whited sepulcher