"Tom's Rhinoplasty" is the eleventh episode of the first season of the American animated television series South Park. It originally aired on Comedy Central in the United States on February 11, 1998. In the episode, Stan Marsh, Kyle Broflovski, Eric Cartman, and Kenny McCormick become infatuated with the new substitute teacher Ms. Ellen, which highly aggravates Stan's girlfriend Wendy Testaburger. Meanwhile, Mr. Garrison gets a nose job that makes him resemble actor David Hasselhoff.

"Tom's Rhinoplasty" was the first Valentine's Day-themed episode of the series and was written by series co-creator Trey Parker. The episode advocates the concept of inner beauty through the Mr. Garrison subplot, and shows the boys' efforts to win Ms. Ellen's affection despite the fact that she is a lesbian.

Natasha Henstridge makes a guest appearance as Ms. Ellen, marking the first time a celebrity guest played a major role in a South Park episode. She is credited as "The Chick from Species" in the opening credits. The episode marked the first time a real photographic image of a person's head (in this case David Hasselhoff) was superimposed over a cartoon body, a practice which would become common throughout the series.

"Tom's Rhinoplasty" introduced the song "No Substitute", which was sung by Chef and was later included on Chef Aid: The South Park Album. Trey Parker and Matt Stone said they were initially unhappy with "Tom's Rhinoplasty" when production of the episode concluded, and were surprised when fans responded positively to it.

Valentine's Day approaches, and Wendy Testaburger suggests to her boyfriend Stan Marsh ways to spend time together. However, when their schoolteacher Mr. Garrison decides to get a rhinoplasty, a new substitute arrives named Ms. Ellen (Natasha Henstridge). Stan, Kyle Broflovski, Eric Cartman, and Kenny McCormick all fall in love with her. Wendy becomes incredibly jealous and warns Ms. Ellen to stay away from Stan, unaware that the substitute teacher does not return Stan's affection.

Concerned about the children's education, Ms. Ellen reveals she will buy dinner for the winner of a spelling test. The boys actively try to court Ms. Ellen, but Chef (having beaten them to it) warns them she is a lesbian and thus only likes other lesbians. The boys do not realize what this means and try in vain to become lesbians in order to attract Ms. Ellen, but misinterpret what others tell them about lesbianism - for example, Cartman, when told by his mother that lesbians "lick carpet", resorts to literally licking the carpet on the floor of his house.

Meanwhile, Mr. Garrison's nose job makes him a "hot and sexy" man, with his face resembling David Hasselhoff, and he decides to quit teaching to pursue women. Stan wins the dinner (much to Wendy's dismay), but finds out that Ms. Ellen has no intention of making love with him. Wendy however sees them through the window and leaves distraught. The next day, several Iraqi men burst into the classroom and declare that Ms. Ellen is actually an Iraqi fugitive, a traitor to the state, and a murderer using a false identity and her real name is "Maqesh Alaq Makaraqesh". Protesting her innocence, she resists arrest and inadvertently kills Kenny in the process by impaling him with a sword to his face. The soldiers take her into custody and shoot her into the center of the Sun via a rocket.

Mr. Garrison becomes a successful model, but he soon finds himself being chased throughout the streets by a large group of women attracted to him. Frightened by all the attention, Mr. Garrison decides to return to his normal looks. Wendy reclaims Stan as her boyfriend after he vomits on her. Despite Ms. Ellen's arrest, Cartman is still trying to become a lesbian by "chowing on [a] box" - that is, literally eating a cardboard box.