|Class||Chordata, Reptilia, Scleroglossa|
|Name Translation||Actaeon Lizard|
Acteosaurus is an extinct genus of aquatic lizard that lived in the Late/Upper Cretaceous Period. Its species, A. tommasinii and A.crassicostatus, were described in 1860 and 1993. Though A.crassicostatus is probably a junior synonym for Adriosaurus suessi, A.tommasinii was found to be similar to coniasaurs, mosasauroids, and a sister taxon to modern snakes in 2010.