I recently rewatched Slither and wrote a review on Letterboxd. Here's what I had to say about it...
SLITHER is a whole lot of fun. I've been saying for a while that James Gunn is a bit like an American Edgar Wright, in that both share an affinity for affectionately lampooning genre fare with films that go beyond mere spoof by actually working as a highly effective example of the kind of film they're homaging. And to carry the analogy further, SLITHER is Gunn's SHAUN OF THE DEAD, a film that is often laugh-out-loud hilarious while also being one of the best schlocky B-movie monster flicks in years.
There are two distinct phases to the film. For the first half hour, I'd argue that the main character isn't ostensive lead Nathan Fillion (on fine deadpan form), but rather Gunn's muse, Michael Rooker. Rooker plays Grant Grant, a downtrodden man in an unfulfilling marriage who is possessed by a genocidal alien parasite. And while the plot dictates that he must feed and spread his contagion through the local population, the film takes a detour as the alien falls in love with Grant's wife, played by the often-underrated Elizabeth Banks, and is taken aback by the fact that he even knows how to love. Rooker is excellent here, and you could have made a whole film out of Rooker's Grant struggling to conceal his monstrous nature from his wife and suppress his base instincts in order to live the new family life he's found himself with. But that's not to be, as this segment of the film gets wrapped up in a surprisingly quick escalation within the film's first half hour.
I briefly mourned the loss of this film-that-might-have-been, as Rooker plays his part so well, and with the script demanding him to disappear for much of the rest of the narrative, the film loses something in his absence. But thankfully, what we get in place of this story in the last hour is heaps of ridiculous, gore-drenched hijinks, as Nathan Fillion's small-town sheriff leads a band of foolhardy souls first in an attempt to hunt down Grant, and then to save the town from an onslaught of alien slugs and zombified townsfolk - though, cleverly, they're not your typical mindless zombies and are instead pitched as obscene parodies of the people they used to be. Things devolve into a film dripping with grue, Gunn evidently relishing the chance to use plenty of old-school practical effects. And the film's influences are broad and shamelessly broadcast: a camera shot straight out of THE EVIL DEAD, a soundtrack riff straight out of PREDATOR, a creature design straight out of THE THING. It's effective as a creature-feature romp, but what makes it stand out is the clever, quirky script from Gunn, acted out by a game cast of comedically-gifted actors. As the town's sleazy mayor, Gregg Henry is a particular standout, which he usually is in the films he's in.
Gunn would go onto refine his craft with SUPER, which even more deftly handles the balance of genre tropes and dark offbeat humor while also injecting an added measure of heart and poignancy, and currently stands as his finest work. But for a feature debut, SLITHER instantly established James Gunn as a writer/director to watch.
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