Earl Jones and only appeared in "Treehouse of Horror". 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 and as candidates on a voting ballot. 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. Characters Creation Kang and Kodos first appeared in the second season in "Treehouse of Horror". The idea of Kang and Kodos came from Jay Kogen and Wallace Wolodarsky, writers of "Hungry are the Damned". In the script, Kang and Kodos were shown as "an octopus in a space helmet with a trail of goo". The finished design was based on EC Comics cover issue. Although originally designed to constantly drool, Matt Groening suggested that they not drool all the time to make the animation process easier. However, the animators did not mind the work, leading to the drooling staying in the script. Kang and Kodos's names are derived from two Star Trek characters. Kang was a Klingon captain portrayed by actor Michael Ansara in "Day of the Dove", whereas Kodos the Executioner was a human villain from "The Conscience of the King". Harry Shearer voices Kang, and Dan Castellaneta voices Kodos. An unofficial rule for the writers is that Kang and Kodos must appear in every Halloween episode. Despite this rule, the writers say the duo will often be forgotten and are only added at the last second, leading to brief appearances. Development Traditionally, Kang and Kodos