Ancylometes is a genus of Central and South American semiaquatic spiders first described by Philipp Bertkau in 1880. Originally placed with the nursery web spiders, it was moved to the Ctenidae in 1967 and in 2025 transferred to the new family Ancylometidae, of which it is the only member. The genus name is derived in part from Ancient Greek "ἀγκύλος" (ancylo-), meaning "crooked, bent".

These spiders live near ponds, lakes, rivers and other freshwater habitats, and can walk on water like water striders due to fine air-trapping hairs on the tips of their legs. They can also dive under the surface, and can stay underwater for over an hour by using the air trapped in hairs surrounding their book lungs. They will consume anything from insects to small lizards and, occasionally, small fish.

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