A key element of Richard Matheson's novel "The Shrinking Man" and the film based on it "The Incredible Shrinking Man" is the struggle of the protagonist, shrunken to the size of an insect, with a voracious spider - ending with his waging an epic battle and killing the spider with a straight pin. Having a human shrunken to the spider's size had essentially the same result as Tolkien's giant spiders, in both cases making the spider a formidable and highly threatening foe.