A Neelix is a person who shares the annoying personality traits with a character of the same name on Star Trek: Voyager.
This person is the most anally retentive person imaginable, the kind of person you would never get tired of kicking. The utmost example of square. No discernable sense of humour. Prone to making "httth" noises (a sharp intake of breath through their face-mounted labia) and growing "hip" little pieces of hair on their faggoty chins, which only reenforces the overall impression of vagina-faced cuntishness. Makes little cuboid shits too.
See also Talaxian
If that guy gets any more square, he'll be a Neelix.