Rethen was the predominant gas in the atmosphere of the gas giant Bespin. It gave the planet its pink hue, had a faintly sweet smell, comparable to that of pancakes drenched with syrup, and was only midly toxic to human lungs.
- Star Wars: Episode V The Empire Strikes Back (First appearance)
- The Empire Strikes Back: So You Want to Be a Jedi? (First identified as Rethen)