Omphalosaurus is an extinct genus of marine reptile from the Middle Triassic. It has generally been considered an ichthyopterygian until Motani (2000) showed that it lacks the basal synapomorphies of Ichthyopterygia. However, Maisch (2010) described a new species and restated its affinity with Ichthyosauria. Several species of Omphalosaurus have been described from the western United States, Germany, and the island of Spitsbergen off the northern coast of Norway.