"Trekker" is what some hardcore fans of Star Trek, who don't like the expression Trekkie for one reason or another, call themselves. Depending on whom you ask, this is either a meaningless distinction, a protest against derogatory connotations with groupie, a sign that one is not a totally obsessed fanboy(or fangirl), or a snobbish self deception about that very same thing.

Trek"ker (?), n. [D.]

One that treks. [Written also trecker.] [South Africa] James Bryce.

© Webster 1913