The answer to the crossword clue “Mr. Krabs Nemesis” is “PLANKTON.” Plankton is a character in the popular animated television show “SpongeBob SquarePants.” He is a tiny and insignificant creature who is the arch-nemesis of Mr. Krabs, the owner of the Krusty Krab restaurant. Plankton is constantly scheming to steal the secret formula for the restaurant’s famous Krabby Patties.