Kang and Kodos have appeared in every "Treehouse of Horror" episode to date, and have played major roles in "Treehouse of Horror I", "Treehouse of Horror II", "Treehouse of Horror VII", "Treehouse of Horror IX", "Treehouse of Horror XVII", "Treehouse of Horror XVIII". " Treehouse of Horror XXII, and "Treehouse of Horror XXX". The rest of their appearances were cameos, although both appeared in the opening segment of "Treehouse of Horror X", "Treehouse of Horror XIV", "Treehouse of Horror XV" and "Treehouse of Horror XVI". In Treehouse of Horror XXXI, Kang and Kodos appeared in flashback segments at the end of the episode. Kang and Kodos's cameo appearances normally occur in the midst of segments, which will suddenly cut away to the duo. For example, Kang and Kodos observe zombies attacking Earth from space. The duo laugh maniacally at the Earthlings' suffering, before the scene is switched back from space to Earth. Kang and Kodos have made rare appearances in non-"Treehouse of Horror" episodes, such as "Behind the Laughter" and "Gump Roast", and had a non-speaking cameo in "The Springfield Files" on a line-up with other aliens.