Leonard Smith is the husband of Joyce Smith, the father of Jerry Smith, the brother or brother-in-law of the Unnamed Uncle, the father-in-law of Beth Smith, and the paternal grandfather of Summer Smith and Morty Smith. He appears in the episode "Anatomy Park". Like his wife, he is a swinger and participates in a three-way relationship with his wife and Jacob Philip where he mainly participates as a voyeur.
Leonard made his first appearance in the episode "Anatomy Park", where Jerry wanted to have a traditional Christmas holiday and kept pushing his family to be lively for when his parents visited. He and Joyce visited the Smith family for Christmas. They also brought along a man named Jacob with them. They explained to their son Jerry that Jacob was a motivational man who lived with them to help bring joy back into their marriages. Jacob's main purpose was to have sex with Joyce on account of Leonard's impotence. Leonard would also watch them doing it from a closet, and according to him, almost always dressed as Superman. Jerry was shocked and he felt very miserable. He ended up hating his parents for this.
Leonard gets enjoyment out of the relationship of Jacob and Joyce by sitting in a chair or closet, watching the two copulate while he is dressed as Superman.
Leonard appears to be a very honest and open man, which occasionally makes his son Jerry uncomfortable.
- He is voiced by Dana Carvey who portrayed Garth in the Wayne's World series and Pistachio Disguisey in The Master of Disguise.