Officer Rob Johnson is a green police fish that appears in many episodes.
He is the head Police of the K9 unit. He appears in Hall Monitor asking Patrick some questions. His last name was revealed in Growth Spout as "Johnson" by Officer John. He also appears in I'm Your Biggest Fanatic as a security guard who is constantly trying to keep Patrick from playing with the displays, and the final straw is when Patrick chases down Jeffery Jellyfish, he goes to confront Patrick.