Kylothians are a malevolent race of strange aliens from the planet Kyloth. They appear to be made entirely of small tentacles, which are wrapped around each other. Only one Kylothian is known, Serleena, who is their Queen and the main antagonist of the second Men In Black movie.
In the end, the Kylothians' plan failed when Serleena was stopped and destroyed by the Men in Black agents Jay and Kay.