Lenford "Lenny" Leonard is a character voiced by Harry Shearer. He works at the Springfield Nuclear Power Plant and possesses a master's degree in nuclear physics, but is not portrayed as an academic. Lenny seems to be a simple, often naïve 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, and is the only person other than the Flanders in church when the town is brainwashed by a cult, suggesting that he may also be a Christian, although many characters of other faiths appear in the church, such as Apu), although he may be like Lisa and goes to church out of Respect for other religions. 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.