The Lone Gunmen were a trio of computer hackers named Langly, Byers, and Frohike. They got their name from one of the reputed JFK theories that it was a "lone gunman" who shot JFK. The LGM were conspiracy theorists and notoriously paranoid (and for good reasons!). They were experienced hackers who often helped Mulder and Scully on cases. Mulder also went to them on information regarding government cover-ups or conspiracies. They shared a loft apartment (where they also worked) and drove a 1970 Volkswagon Transporter (mobile command unit!). They also published a newspaper called "The Lone Gunmen" which dealt with conspiracy theories and the paranormal (which Mulder subscribed to, of course).
(Info on the trio)
Langly: Richard "Ringo" Langly, the expert hacker, trademark long hair, glasses, Ramones shirt, and converse shoes, RPG alias: 'Lord Manhammer", his list of things he detests (from lgm site) Easy listening music, especially Celine Dion, IBM mainframes, Everything made by Microsoft, Smurfs, Ewoks, Beanie Babies and other forms of offensive cuteness, Bureaucracies, Women who don't want to date me (approx. all women), Stuck-up supermodels, Losing lives at Dungeons & Dragons, Jocks (but Jimmy is okay sometimes), Stupid people (but Jimmy is okay sometimes), Cows, Hair in the shower (Frohike), Sticky play buttons on VCRs (Frohike), Business suits (and other Byers nerd-wear), Dishonesty, Poverty, Boredom, COBOL, BASIC, Character-based menu interfaces, Byers obsession w/ proper grammar, When Yves screws us over for money
Frohike: Melvin Frohike, he's a dirty old man (but we still like him), photographic and surveillence specialist of the group, used to sell illegal cable descramblers, tango king?, has a crush on Scully
Byers: John Fitzgerald Byers, he has the "calm intelligence" of the group, born same day JFK was assassinated, used to work for the FCC, has a crush on Suzanne Modeski, always wears suits