A government official who helps and hinders our heroes. He is usually more of an annoyance than a help until Water Hazard when Tyler and Rosalita need a way to block a creature from escaping while they dump dry ice on it and he heroically drives his car into the river, blocking its escape and allowing it to be killed.
A federal agent who moved to Bixby so that the government could monitor the area. He once mentioned having a wife and child, but they have never been seen. While he is technically a series regular (along with Burt, Nancy, Jodi, Tyler and Rosalita), he is a rather minor character in the franchise overall, as he has no connections to any characters in the films.
Twitchell and his family live in Bixby, in a "ranchette" style home built by developer Melvin Plugg. Twitchell works out of an office in Las Vegas. While he is level GS 13 (mid level pay grade) in the U.S. government, and would normally have a staff, the position of monitoring Perfection valley, the world's only designated Graboid habitat, is so unusual, and the people in the valley so few, the powers that be placed him in charge alone.
W.D. Twitchell is a wiry, nervous man in his late forties. He is an agent of the U.S. Department of the Interior, assigned to monitor the Endangered Species Habitat that is Perfection Valley. He hates his job. Hates the desert. He carries a small, battery-operated fan when he makes his periodic inspections of Perfection's barren landscape. Sometimes he refuses even to get out of his air-conditioned government sedan, preferring instead to talk to people through a small gap in his tinted-glass window. He's terrified of El Blanco — and any other creature he meets. But Twitchell hangs in there, looking forward to the promotion his superiors dangle as a carrot — a comfortable assignment in a much nicer spot, like Yosemite.
Twitchell has the authority to evict everyone from Perfection Valley should he decide their co-existence with El Blanco is just too dangerous — for them or for the albino Graboid. Though he can be affable, he's not above employing underhanded tactics if he thinks they might get him out of this gig and up the DOI ladder.
Twitchell would be much closer to realizing his dream (and lowering his stress level) had his boss not made him the point man on any investigations into possible Graboid activity outside Perfection Valley. Twitchell, realizing he needs expert help on such assignments, has struck an uneasy deal to subcontract the work to Burt Gummer.
When Burt and his partner, Tyler Reed, go off to solve other people's monster-related problems, Twitchell occasionally will pop up to monitor the mayhem in Perfection and put a reassuring spin on the potentially bad public relations that surely will be caused by Shriekers running amok in the local shopping mall.
Basically, Twitchell thinks the townsfolk should "give up" and go live in nice, suburban tract homes "like normal people."
However, it is worth noting that every time he has an opportunity to protect the town and the people's lifestyles, he takes it, even once stating that Perfection is "his town too." He may not be as opposed to their lifestyle and his job as he makes out.
- Tremors: The Series