Billy is a kid fish who first appears as the secondary antagonist of the episode "Friend or Foe."
He is a light purple fish with purple fins, faded-blue lips, and wears a red shirt and a white and blue cap.
Billy likes to bully innocents with no apparent reason behind his actions, as seen in the flashbacks from his grade-school years and when he is shown as a delinquent teenager using ketchup as a weapon.
Role in series
"Friend or Foe"
Billy is shown as the leader of a group of class bullies at Poseidon Elementary School who constantly makes fun of Mr. Krabs about his clothes and calls him "Rag Boy" and also bullies Plankton for his small size and brilliant intelligence.