Known as the "Gruesome Twosome," Patty and Selma Bouvier are Marge Simpson's older, chain-smoking twin sisters. Patty and Selma both work at Springfield's Department of Motor Vehicles and share an apartment together at the Spinster City Apartments.

They share a passion for watching the tv show McGyver, smoking cigarettes, travelling together and of course, ridiculing their brother-in-law, Homer. Patty and Selma were not very loving sisters to Marge growing up. They used to make her clean their room and perform their chores, they tormented Marge about her first day of school and even leaked the news of Marge's pregnancy despite her asking them not to. Another problem for Marge is that both sisters hate Homer and are constantly insulting him in front of Marge.

Despite their similarities, Patty and Selma do have their differences.

Selma, the younger twin, is distinguishable from Patty by the middle part in her hair, her circular shaped earrings, necklace beads and light-blue dress. Selma has no sense of smell which was a consequence of a freak bottle-rocket accident. Some of Selma's favorite things include spending time with her iguana "Jub Jub", smoking her Laramie Hi-Tars and of course, watching McGyver.

Unlike her twin, Selma has had several romantic relationships and has even been married three times (though all marriages were unsuccessful and ended in divorce). Selma's first marrige was to the evil SideShow Bob Terwilliger who was her prison pen pal. Selma's marriage to Bob ended after he tried to murder her. Selma was also married to Lionel Hutz briefly. Selma was also married to actor Troy McClure. Troy married Selma to further his career and image but he couldn't make himself love Selma. When Selma realized that she was in a loveless marriage, she dissolved the marriage and returned to live with Jub Jub and her sister, Patty.