Selma Terwilliger-Hutz-McClure-Stu-Simpson-D'Amico (née Bouvier) (born 1951) is one of Marge's older chain-smoking twin sisters. She works at the DMV and possesses a strong dislike for her brother-in-law, Homer, although on extremely rare occasions she shows kindness towards him and seems to tolerate him. Selma is often somwhat old lady like and extremely unnatractive Selma is the adoptive mother of Ling.

Selma Bouvier was born two minutes before Patty. Due to a childhood bottle rocket accident, she lost the sense of taste and smell. Selma's favorite film actor was reportedly Troy McClure, to whom she was briefly married, before discovering that it was just a publicity stunt by McClure. McClure took it one step further by wanting to have a child with Selma to help his career. Selma was willing to live a sham for a while, but broke it off when she realized she couldn't bring a child into a loveless marriage. According to Marge, Selma is "the one who likes Police Academy movies and Hummel figurines, and walking through the park on clear autumn days." Selma inherited her deceased Aunt Gladys's iguana, Jub-Jub, instead of her mother, Jacqueline, due to Jacqueline's dislike of Jub-Jub. Unlike Patty, Selma is very desperate to find love after seeing her Aunt Gladys' video will. She also asks Marge for advice to find love, saying that Patty is 2 minutes younger than she is.

Selma's favorite brand of cigarettes is identified as "Laramie Hi-Tars" while Patty's favorite brand of cigarettes is "Lady Laramie 100s"; they have been claimed by their mother to "have started smoking even before birth". It is shown that Patty and Selma started smoking as children when they gave their allowances to Marge (she would do their chores), and with all the free time they had, they took up smoking. The twins had melodic voices prior to starting smoking, and their trademark harsh voices after. The smoke and ash from the cigarettes turned her hair grey, originally blond. Patty and Selma share an apartment at the Spinster Arms apartment complex and work at the Department of Motor Vehicles (DMV). They have on numerous occasions acted unprofessionally in the course of their jobs.

Selma and Patty both have an avid (sometimes maniacal) love of the television show MacGyver. Selma nearly broke off her engagement with Sideshow Bob because he disliked the show, and both Patty and Selma stay up until two in the morning to watch the show. Patty and Selma both have an interest in travelling. The twins have visited Egypt, Lenin's Tomb in St. Petersburg, Russia, Easter Island, and Mexico but more mundane places, such as the Horse Drawn Carriage Museum in Alberta, Canada. When they return home, they bring back numerous slides of them in these locales, and show them to the Simpson family, often describing the events in the most unenjoyable way possible. The family, especially Bart and Lisa, are shown as barely staying awake during these shows.