Nosferatu

Nosferatu is a character who appears in the episodes "Graveyard Shift" and "The Night Patty," and the DS version of the video game SpongeBob's Truth or Square. He is a vampire from the 1922 horror film of the same name.

Description
He is a vampire who wears black attire. In "The Night Patty," he is shown wearing a darker-colored version of the Krusty Krab employee hat.

"Graveyard Shift"
Nosferatu is responsible for the light flickering at the Krusty Krab, which confuses and scares SpongeBob and Squidward, as the lights flickering is one of the signs of the hash-slinging slasher's arrival.

"The Night Patty"
Nosferatu hides in the cooler during the night shift and is the boss there. He approves SpongeBob to be a fry cook for the night shift by drinking his blood with a straw.

SpongeBob's Truth or Square
He appears in one of the mini-games in the DS version.

Trivia

 * Contrary to popular opinion, the word 'nosferatu' does not mean 'vampire', 'undead', or anything else like that. The term originally came from the old Slavonic word 'nosufur-atu', which itself was derived from the Greek 'nosophoros'. 'Nosophoros', in the original Greek, stands for 'plague carrier'.
 * "The Night Patty" marks the first time Nosferatu's full body is shown in SpongeBob SquarePants.
 * His appearance in this episode also marks his first in-series appearance in 17 years.
 * He replaced "Floorboard Harry" in the final draft of "Graveyard Shift."
 * Irony: Nosferatu is a land-based character, like Sandy Cheeks, Wormy, and Kenny the Cat. But unlike them, he doesn't have an air helmet to breathe, but somehow still survives underwater.