Lenny is an anchovy who has appeared in many episodes as a background character, starting with "Ripped Pants."
He is usually a light blue anchovy who wears a light tan shirt, making him look more like one of the basic blue anchovies from "Help Wanted." He also is commonly seen with a white dress shirt with a red tie along with a black fedora, dark blue pants, and black shoes.
Throughout the series, despite usually resembling one of the basic blue anchovies from "Help Wanted," he is always seen alone with other kinds of fish instead of appearing in a large swarm of anchovies, though he has also been seen with a dress shirt in many episodes, making him look a little less similar to the basic blue anchovies. He is also capable of speaking English instead of just saying "meep."
He makes his debut in "Ripped Pants" where he is one of the many beachgoers laughing at SpongeBob when he rips his pants.
In "Something Smells," he and his wife, Mable-Monica, pull a fishing hook down to the bottom to the ocean to escape SpongeBob's rancid breath.