Askeptosaurus is an extinct genus of aquatic reptile belonging to the diapsid group. It was about 2 m (6 ft 8 in) long.

Askeptosaurus was a very thin, elongated creature that probably swam like an eel. It steered using its webbed feet. Judging from its long jaws, it was a fish eater. Paleontologists think Askeptosaurus hunted in deep waters, based on its large eyes (which would allow it to see better in dark water) and the protective bony ring around its them (also seen in ichthyosaurs), which prevented them from getting squashed in by the immense water pressure at great depths.