Harold William "Bill" Fish is a cameo character seen in many episodes. He is a blue fish who has a shark-like fin who loves to eat at the Krusty Krab.
He is a torch lighter at the Fry Cook Games in the Fast Food Coliseum. His name is revealed in the episode Roller Cowards when he fell out of the Fiery Fist O Pain and Nancy shouted "Harold! No!!!" in the ride promotion. His name is also mentioned in the episode Gary in Love. Harold works at Glove World, as the person who checks people if they are okay to ride the Fiery Fist O Pain. In Jellyfish Hunter, he and Nat Peterson tried to sell SpongeBob something. In Gary in Love, Harold was a pet shop worker, and had a black shirt. He said "Harold didn't do it, didn't do it Harold."
He went to the Komedy Krab and also Squidward's Talent Show. He is not to be confused with Mr. Krabs' alter ego "Harold Flower", a name used in the episode Born Again Krabs. In some episodes,(Squirrel Jokes, Band Geeks, Sun Bleached) he has an Australian accent. Harold first appeared in the episode "Ripped Pants". He is Peterson's best friend. And he was seen as one of the customers in The Chum Caverns in the episode Chum Caverns. In Grandma's Kisses he teased SpongeBob, while he got in. He said Oh yeah we're definitely out of here! in Your Shoe's Untied. In Christmas Who? he wears a black t-shirt.
Harold is cyan-skinned. He wears a white shirt, red shorts, and red vans sneakers and a shark-like fin. In the episode "Your Shoe's Untied," he was seen nude. And again in The Battle of Bikini Bottom and Stanley S. SquarePants. But he is seen skinnier in the episode Ripped Pants (Episode)
 Harold's house
Harold's house is one of houses downtown. The only part of his house shown is the bathroom in the episode "Pranks a Lot".
- In the episode "Porous Pockets," Harold's friend Bert calls him Bill.
- In Sailor Mouth, he is dressed as a pirate and speaks like one too.
- In Roller Cowards, when he is working at Glove World, he wears a tan shirt.
- In Le Big Switch, Jellyfish Hunter, and Patty Hype, he is seen in a brown suit and fedora hat.
- In Patty Hype, it is revealed that Harold's favorite color is purple.
- In Pranks a Lot, Harold's bathroom is shown.
- He has a yellow-orange boat in Truth or Square? and Hall Monitor.
- He plays multiple musical instruments.
- In Gary in Love, it is shown that he can communicate with snails.
- His voice actor is Danny Jacob
- In Band Geeks when he said "Big Meaty Claws" he was also talking about Larry the Lobster.
- In some episodes, he is a rude fish who speaks in a heavy Australian accent.
- It is known he is scared of mermaids as he ran away from SpongeBob screaming mermaid in The Curse of Bikini Bottom.
- He Spent 20 years training to climb but he never became the first to climb Mt. Bikini Bottom as he let the chance go when SpongeBob and Squidward blew off a ballon and landed on the mountain in Are You Happy Now?.
- He was called some random guy by SpongeBob in Planet of the Jellyfish.
- In the episodes Your Shoe's Untied and Hooky, he is naked.
- "Did he just say?" (Sailor Mouth)
- "Sir, you have a serious medical condition." (Roller Cowards)
- "Well, maybe we wouldn't sound so bad if some people didn't try to play with big meaty claws!" (Band Geeks)
- "Just don't move, or breathe, he might go away." (Porous Pockets)
- "That patty's green!" (Patty Hype)
- "I told you he was onto us!" (Jellyfish Hunter)
- "You know, this stuff is hideously inedible." (Chum Caverns)
- "I mean look at you! Do you hug your mother with that skin?" (Sun Bleached)
- "Get off of me! (Mid-Life Crustacean)
- "Dude, can I have some ketchup?" (Graveyard Shift)
- "Two hours is long enough!!" (Bubble Buddy)
- "Congratulations." (Bubble Buddy)
- "Harold didn't do it, didn't do it Harold." (Gary in Love)
- "Big Meaty CLAWS!!" (Band Geeks)
- "I declare these Fry Cook Games... open!" (The Fry Cook Games)
- " Thanks (once bitten)
- " parden me thanks (once bitten)