3rd Rock from the Sun - Season 4 Episode 20 Alien Hunter

It is the day before Dick's birthday and he has ordered Sally, Harry and Tommy to throw him a surprise party. When in class he meets a woman called Charlotte Everly who appears to be very taken by his 'brilliance'. Charlotte first claims to be auditing his class, then later claims to be a reporter, then an intellectual groupie. She and her son wangle her way into his birthday plans, cancel his party and lock the guests that do arrive in the basement. She then reveals to Dick that she knows that Dick is an alien - and she wants to cut him open. Kathy Bates' appearance in this episode spoofed her role in the film Misery, when Dick refers to her as his "number one fan".