"Lenny" Leonard is a fictional character in The Simpsons, voiced by Harry Shearer. He works at the Springfield Nuclear Power Plant, and is known for getting various objects stuck in his eyes. Lenny possesses a master's degree in nuclear physics, but is not portrayed as an academic. Lenny seems to be a simple, often naive blue-collar working man whose best friend is Carl Carlson.

He is also a war hero, a three-time juror and a Buddhist (although he is often shown in Reverend Lovejoy's church, suggesting that he may also be a Christian, although many characters of other faiths appear in the church, such as Apu). During one episode, he showed himself to be an extremely adept guitar player. Lenny was also member #12 of the Stonecutters which was disbanded to form the "No Homers" society.

Lenny is unmarried (although in the episode "Sleeping With The Enemy", Lenny remarks that Carl sang at his wedding) and between 35 and 40 years old (born the week of a massive bloody battle in Laos), and weighs approximately 164 pounds (75kg). He looks to be around 5' 11" (1.8m), and is often described as "plain looking". He had plastic surgery when a sudden upswing in the price of power plant stock led to most of the employees (with the exception of Homer) to have a big profit. In one episode it is revealed his real name might actually be 'Lenford Leonard', though the audience cannot be certain if this was just a joke. In the episode "The Seemingly Neverending Story" Lenny reveals one of his other vices aside from drinking at Moe's, which is dressing up like a baby.