He has the same form as Plankton but has a large light brown beard, wears a light orange-yellow waistcoat, a white shirt, black pants and shoes. SpongeBob thought he was really Dr. Peter Lankton when he is really Plankton.
Role in episode
When SpongeBob thinks he is seeing killer Krabby Patties, he goes to see Dr. Lankton, a supposed psychiatrist. However, he is actually trying to get SpongeBob to tell him the secret formula. After many failed attempts, like using hypnotism and an ingredient combination, SpongeBob feels better and goes back to the Krusty Krab.
Dr. Lankton tells him that therapy does not work and that he is still sick, but SpongeBob ignores him.
The name Peter Lankton has the "P" removed from "Plankton" and made into Peter.