Neptune, is the home world of Kalnik, the alien observer turned intent on world domination, and wiping Mork out.
About[]
Neptune is in the same Solar System as Earth, which is why, when Mork informs Mindy of his meeting/conversation with Kalnik, she is very surprised to hear there is life on Neptune. He jokes that there isn't, after dark, except for one good rib place. (Gotta Run, Part 1)
Kalnik's initial job is to report back to Neptune on Earth's advancement before he goes off track. However, once things go sideways with Kalnik, Mork tells Mindy that the Neptunians are quite a blood thirsty people, who 'finish their anthem' with a living sacrifice.
Their powers are telekinetic and, according to Kalnik, at least, more powerful than Morks, which bears out in their duel, as it takes all three of the McConnell's to overcome him. Mork's non violent philosophy would of course hold him back.
Neptunians are long lived like Orkans, with Kalnik's parents about to celebrate their 400th Anniversary, at which stage in their lives they are still 'very alert'. (Gotta Run, Part 3). They also have access to time travel devices, as shown by Kalnik's pursuit of Mork & Mindy through time.