"Trekker" is a slang term for a Star Trek fan. Many Star Trek enthusiasts prefer to be identified as "Trekkers" rather than "Trekkies", perhaps because "Trekkie" is perceived as parallel to "groupie".
A trekker, or trekkie, is a die hard fan of the Star_Trek television and movie dynasty. Some trekkers also attend Star Trek conventions (which the current author swears to know nothing about).
Amongst trekkers can be found speakers of the artificial Klingon language.
Trekkers have been parodied in several films including Galaxy Quest.