Patricia Maleficent "Patty" Bouvier and Selma Bouvier-Terwilliger-Hutz-McClure-Discotheque-Simpson-D'Amico are fictional characters in the American animated sitcom The Simpsons. They are identical twins and are voiced by Julie Kavner, who also voices their sister, Marge. Patty and Selma, both gravel-voiced chain-smokers, work at the Springfield Department of Motor Vehicles. They have a strong dislike for their brother-in-law, Homer Simpson, who likewise loathes them. Selma, the elder by two minutes, longs for male companionship and has had multiple brief, doomed marriages, and has herself offered help in some fashion to Marge and Homer as she envies their loving relationship; she receives occasional compassionate support from Homer who even poses as her husband to help her adopt a child. Patty is an initially closeted lesbian who embraces celibacy until she begins dating women. Kavner voices them as characters who "suck the life out of everything". Patty and Selma debuted on the first Simpsons episode "Simpsons Roasting on an Open Fire", which aired on December 17, 1989.

Robert Underdunk Terwilliger Jr., PhD, better known as Sideshow Bob, is a recurring character in the animated television series The Simpsons. He is voiced by Kelsey Grammer and first appeared in the episode "The Telltale Head". Bob is a self-proclaimed genius who is a graduate of Yale University and a champion of high culture, including the adoption of a transatlantic accent, similar to that of Grammer's portrayal of Dr. Frasier Crane from the sitcoms Cheers and Frasier. He began his career as a sidekick on Krusty the Clown's television show, but after enduring constant abuse, Bob framed his employer for armed robbery in "Krusty Gets Busted", only to be foiled by Bart Simpson, and sent to prison. Bob started seeking revenge against Bart while in prison, and the two became feuding arch-enemies.