Marionette is one of two parts of a mort named Wilhelm Faulkner, who was a manipulative and ruthless child serial killer who created Fazbear's pizza as a means to draw children in so he could kill them. He represents the passive and manipulative parts of his personality.
The Puppet has a white face with black, hollow eyes (aside from its jump scare, and a small in-game cutscene, where it gains small white pupils). Its face is similar to that of a Pierrot, with rosy red cheeks, purple stripes that stretch from the bottom of its eyes to the top of its mouth and red lipstick painted on in an exaggerated pucker.
Its body is somewhat reminiscent of a sock monkey's, with its round, oblong shape, thin waist, white buttons, rounded hands that feature three spindly fingers each and white stripes on the wrists and ankles. Technically speaking, it has no feet, but its legs are tapered to a point. It has neither hair nor head accessories. It's quite lanky, and according to one of the hallucinations in which it appears, it stretches from the floor to the ceiling of the pizzeria.