"Treehouse of Horror IX" is a Halloween-themed episode from the tenth season of the animated comedy series The Simpsons. It was first broadcast in the United States on the Fox Network on October 25, 1998.
In common with the previous Simpsons Halloween specials, the program is made up of three self-contained stories; "Hell Toupee", "Terror of Tiny Toon" and "Starship Poopers". In "Hell Toupee", Homer Simpson gets a hair transplant. The hair he receives had belonged to the executed dangerous criminal Snake. At night, Snake's hair takes over Homer's mind to take revenge on the witnesses who saw him commit his final crime. In "Terror of Tiny Toon", Lisa and Bart Simpson's lives are in danger when they find themselves inside a Halloween episode of their favorite violent cartoon show. In "Starship Poopers", it is revealed that the baby girl Maggie is really the daughter of the alien Kang.
The opening credits sequence is a variation of the show's normal one but is given a horror twist. Using a jack-o-lantern as a paint pot, Bart Simpson paints the words "The Simpsons Halloween Special IX" in blood on the chalkboard in his classroom. Each member of the Simpson family has a fatal accident in front of their garage. Inside the Simpsons' house, Freddy Krueger and Jason Voorhees sit on the couch. They comment that it is odd that the family members have not yet arrived home but decide to stop worrying about it and watch TV.
The notorious criminal Snake is arrested for smoking inside the Kwik-E-Mart convenience store. As police officer Chief Wiggum takes Snake away, he points out that it is Snake's third offense and he will be executed for it. He adds that Snake's arrest was only possible thanks to the three witnesses; Apu the convenience store clerk, Moe the bartender and young Bart Simpson. After Snake is executed, his organs are used for transplants.
Bart's bald father Homer Simpson gets a hair transplant. The hair, of course, comes from Snake. At night, the hair's roots enter Homer's brain, taking over his mind. On two consecutive nights, Homer goes out and takes revenge on the witnesses who sent Snake to the electric chair, killing Apu and Moe.
Knowing that the other two witnesses have been killed, the terrified Bart is certain that he will be next. Homer vows to protect his son, locking himself in a room with the boy. Snake's hair then begins to take control of Homer, causing him to threaten Bart with a sledgehammer. Bart tells his father to fight the hair. Homer does so, ripping it off his head. However, the hair takes on a life of its own and jumps on Bart's face to smother him.
Chief Wiggum arrives to arrest Homer for the murders of Apu and Moe. Homer says that the hair was to blame. The hair tries to escape out of a window but Chief Wiggum shoots it before it can get away. Chief Wiggum comments, "Now, that's what I call a bad hair day". All of the Simpsons laugh at that, except for Homer's wife Marge who points out that two people have died. Shortly afterwards, she gets the joke and begins laughing too.
"Terror of Tiny Toon"
On Halloween night, Marge Simpson is preparing to take her baby daughter Maggie, dressed in a pirate costume, out trick-or-treating. She is disappointed to see that her husband Homer is dressed in a hobo costume again, although Homer's comments reveal that he is not wearing a costume.
Marge leaves Homer and her two older children Bart and Lisa at home. She forbids her children from watching the Halloween special of their favorite cartoon series, The Itchy and Scratchy Show, saying that it is too violent. She takes the batteries out of the remote control to make sure that they cannot watch TV.
Once Marge has gone, Bart takes some plutonium, which Homer brought home from his job at the nuclear power plant, and puts it inside the remote control in place of the batteries. When Bart and Lisa fight over the remote control, they accidentally press the button marked "enter" and find themselves inside the cartoon show. They laugh when Itchy the mouse uses the head of Scratchy the cat to make a jack-o-lantern. However, both Scratchy and Itchy are shocked that the children laugh at the cat's pain. They team up and chase the children, brandishing deadly weapons.
Homer watches and enjoys the cartoon for a short while, not appearing to be surprised to see his son and daughter in it. He then tires of it and changes the channel, briefly sending Bart and Lisa (in a live action sequence) into Live! with Regis and Kathy Lee. The children manage to communicate with their father through the TV, telling him to find the right button on the remote control to bring them back. While Homer is searching for the correct button, Scratchy aims a hose full of piranhas at Bart. The fish eat Bart's body, leaving him as a skeleton from the neck down.
Homer eventually finds a button which brings the children back, Lisa presses "rewind" and restores Bart's body, but Itchy and Scratchy follow them out of the TV. The Simpsons are frightened of the ax wielding animals at first but then notice how small they are, being merely the size of an ordinary mouse and cat. The Simpsons decide to keep the two animals as pets. Scratchy the cat immediately falls in love with the Simpsons' cat Snowball II, but is horrified when he is told that he will have to be neutered as a result.
The youngest member of the Simpson family, the baby girl Maggie, grows her first tooth, a long sharp fang. Shortly afterwards, her legs drop off and long green tentacles appear in their place.
The aliens Kang and Kodos arrive at the Simpsons' home, saying that they have come to take Maggie back to their own planet. Marge reveals that Kang is Maggie's real father. Nine months before Maggie was born, Kang and Kodos abducted Marge to use her in a cross-breeding program. The program involved Kang sitting next to Marge on a couch and attempting to use lousy pick-up lines on her, before saying "Look over there!" When Marge turned to look, Kang fired a ray at her which made her pregnant.
Homer Simpson and Kang begin to fight over who should have custody of Maggie. Bart tells them that there is only one place where the matter can be settled - on The Jerry Springer Show. Homer and Kang continue to fight and swear at each other on the show. When an audience member accuses Kang of not acting like a real father, he vaporizes her. At the end of the show, Maggie attacks Jerry Springer while Kang and Homer begin to fight again.
After the show, the Simpsons comment that Jerry Springer was unable to solve their problems and will not be able to now because Maggie has killed him. Kang and Kodos say that if Maggie is not returned to them, they will murder every politician in Washington D.C. The Simpsons slyly comment that the aliens could not possibly kill every politician. Kang and Kodos assure the Simpsons that they can and leave to begin their task. After they have gone, Maggie announces in an alien voice that she wants to drive the car and that she needs blood.