"Not It" (titled onscreen as "Treehouse of Horror Presents: Not It") is the fifth episode of the 34th season of the American animated television series The Simpsons, and the 733rd episode overall. It aired in the United States on Fox on October 23, 2022. The episode was directed by Steven Dean Moore and written by Cesar Mazariegos.

The episode is a parody of Stephen King's 1986 supernatural horror novel It and its film adaptations, It (2017) and It Chapter Two (2019). The episode received positive reviews. Maggie Simpson does not appear in this episode.

From September 29 to October 9, 2022, a contest was held that allowed viewers in the United States to submit spooky Krusty fan art. The works of 20 winners were presented during the credits of the episode.

In 1990, Barney encounters Krusto, who drags him into the sewer. While looking for Barney, Homer is attacked by bullies. Seeing Krusto watching them, he calls the clown for help and escapes with the bullies following. The Losers, consisting of Marge, Comic Book Guy, Carl and Moe, defend Homer, and the bullies run away. The Losers and Homer share stories of their encounters with Krusto. They discover Krusto had several unfunny shows over many years, and he resurfaced every 27 years to kill children. As Marge and Homer show a clip from Krusto's 1963 show, Krusto emerges from the television and tries to kill Comic Book Guy. Homer stabs Krusto before Marge shuts the television off.

They go to the television studio to defeat Krusto. Homer opens a box, revealing Krusto hidden inside. The Losers ineffectively attack Krusto. When Krusto slips and hurts himself, the children laugh, which surprises Krusto as children have never laughed at him before. Krusto hurts himself for laughs until Marge gives him some cherry bombs to eat. Krusto explodes but slithers down a drain. They promise to reunite in 27 years to kill Krusto permanently. Marge kisses Comic Book Guy, who took credit for a poem that Homer wrote for her earlier.

In 2017, Marge and Comic Book Guy are married and have two children named Bert and Lizzie (the Simpson children with reversed personalities). When bullies are killed by Krusto, Homer calls the Losers to help him defeat Krusto. Comic Book Guy refuses to help, so Marge goes by herself. As they plan how to defeat Krusto, Comic Book Guy arrives with the kids to retrieve Marge. Marge tells the kids to wait outside while she argues with Comic Book Guy. Krusto notifies the Losers that he has kidnapped Bert and Lizzie.

They return to the studio and tell Krusto they no longer have childhood fears. Krusto says adults have anxieties and shows them as he grows more powerful from the laughter of his ghost audience. He reveals that Comic Book Guy did not write the poem. Bert and Lizzie see his power comes from the sign commanding the audience to laugh. Homer gives Marge a rock to throw at the sign, and Marge realizes that Homer wrote the poem. When Krusto tries to eat Marge, Comic Book Guy jumps in the way, allowing Marge to destroy the sign. The ghosts ascend to Heaven as Krusto dies. Though Marge admits that she cannot forgive Comic Book Guy for lying to her, she is proud her dying husband was brave. Bert, Lizzie and the surviving Losers ride out of the ruins, and Homer and Marge get together.

Kang and Kodos realize their plan has failed and look through other Stephen King books to choose what to do next.