Old Man Walker is an elderly fish who makes many appearances in the series, usually as a side character. He first appears in the episode "Mermaid Man and Barnacle Boy."
He is a short light green elderly fish with light orange liver spots on top of his head. He usually wears a light blue shirt and wears thick glasses. He is also mostly seen with a bamboo walker which is what gives him the name "Old Man Walker."
Throughout the series, he appears as a side character. He can usually be seen eating at the Krusty Krab.
In "The Algae's Always Greener," he runs into a Krusty Krab support beam and tells it, "pardon me, young lady." He then grabs the ketchup bottle that Plankton is hiding in and accidentally shoots him right through the wall of Mr. Krabs' office due to his lousy aim.