Slither (2006)

Small-town lawman Bill Pardy (Nathan Fillion, having a blast) is charged with protecting the province of Wheelsy just as a meteor lands and a space bug with a mission -- a reproductive mission -- hatches. Freakin' alien terrorist cells, I tell you what. The critter isn't choosy for a mate, picking the first target of opportunity, happens to be town boss Grant Grant, out in the woods with his mistress Brenda since his wife back home (the lovely Starla, who also happens to be Pardy's old unrequited love) won't give him any, boo hoo. Take a pinch of Alien (1979), a dash of Die Monster Die (1965), garnish liberally with some From Beyond (1986), next thing you know Grant has mutated into a giant space slug and taken up stealing raw meat so he can feed Brenda, whom he's tucked away in an abandoned barn while she... gestates. Not to give it away, an unholy rain of brain-eating space slugs ensues. Something for everyone. Lovecraftian homage to creature features of yore; James Gunn's witty script and direction target the funny bone as much as the gross-out gizzard. This is how a dud becomes an underground cult classic.