The Gotal Hennet Kayn was present in the spaceport of Mos Eisley on the planet Tatooine in the year 0 BBY, during the Galactic Civil War between the Galactic Empire and the Alliance to Restore the Republic. Shortly before the Battle of Yavin, the Gotal was in Chalmun's Spaceport Cantina in Mos Eisley when the smuggler Han Solo attempted to leave the establishment, only to be forced back into his seat by the bounty hunter Greedo.
As Solo and Greedo discussed the bounty on the smuggler's head, Kayn walked from the direction of the cantina's main bar into a booth, where the Abyssin Myo and the Talz Muftak were seated. Solo and Greedo then exchanged blasterfire, with Solo killing the bounty hunter, which briefly drew the attention of many patrons in the cantina.
Hennet Kayn used components from the costumes of several other cantina characters.
Hennet Kayn first appeared in the 1977 original trilogy film, Star Wars: Episode IV A New Hope. The character's costume was made up of items from the costumes of several other Mos Eisley Cantina patrons, including Trinto Duaba's robe, M'iiyoom Onith's shirt, and a mask and claws used by fellow Gotals Feltipern Trevagg and Cobb Sonbepol. The mask was designed by conceptual artist Ron Cobb and created by makeup artist Laine Liska.
Costume designer Rick Baker had originally created the claws as props for the 1974 horror film It's Alive. Liska modified the claws with fur for Star Wars. The cantina character Myo also used a separate pair of the same claw props but without the fur.
The Hennet Kayn character name was first created at the "Behind the Scenes of the Cantina" panel at Star Wars Celebration Chicago in 2019. After panel host Tom Spina discovered production images of Kayn, he and Lucasfilm Story Group member Leland Chee named the character based on panel attendee Kenneth Haynie, who won the honor during the panel.