Slither (2006)

Slither is a 2006 science fiction-horror-comedy film written and directed by James Gunn, and starring Nathan Fillion, Elizabeth Banks and Michael Rooker. The film was produced by Paul Brooks and Eric Newman. Slither is James Gunn's directorial debut.

Plot: A meteor housing a malevolent alien parasite crashes into the town of Wheelsy, South Carolina. While frolicking in the woods with Brenda (Brenda James), local big shot car dealer Grant Grant (Rooker) is subsequently infected and killed by the parasite. The parasite takes over his body and absorbs his consciousness and memories. With the alien (called "The Long One") now in control of his body, 'Grant' begins to slowly change into a hideous tentacular sluglike monster.

No one suspects Grant of the serial pet murders that have occurred around town, however his wife Starla (Banks) begins to question his health. He avoids doctors appointments and crafts lies to keep her in the dark. Sensing her distance from her husband, her childhood crush, town sheriff Bill Pardy (Fillion), attempts to reassure and comfort her while not acting on his own feelings.

Grant infects the lonely and neglected Brenda with hundreds of his "offspring." He secrets her in an isolated barn where she in turn becomes massively obese as baby alien slugs grow inside her. Sheriff Bill Pardy leads a small group of officers on a hunt for Grant only to be lured into a trap where Brenda explodes releasing hundreds of the alien slugs. Most of Pardy's group become infected, zombie-like creatures. Strangely, the infected begin to want Starla and talk to her as if they are Grant.