Aegirosaurus is an extinct genus of platypterygiine ophthalmosaurid ichthyosaurs known from the late Jurassic and early Cretaceous of Europe. It was originally named as a species of Ichthyosaurus.

Ophthalmosauridae is an extinct family of thunnosaur ichthyosaurs from the Middle Jurassic to the early Late Cretaceous worldwide. Almost all ichthyosaurs from the Middle Jurassic onwards belong to the family, until the extinction of ichthyosaurs in the early Late Cretaceous. Ophthalmosaurids appeared worldwide during early Bajocian, subsequent to the disappearance of most other ichthyosaur lineages after the end of the Toarcian. Currently, the oldest known ophthalmosaurids is Mollesaurus from the early Bajocian of Argentina, as well as indeterminate remains of the same age from Luxembourg and Canada. Named by George H. Baur, in 1887, the family contains the basal taxa like Ophthalmosaurus. Appleby (1956) named the taxon Ophthalmosauria which was followed by some authors, but these two names are often treated as synonyms; Ophthalmosauridae has the priority over Ophthalmosauria. However, some researchers argue that Ophthalmosauridae should be restricted to the group typically referred to as Ophthalmosaurinae, with classic Platypterygiinae instead being referred to as Undorosauridae or Brachypterygiidae and Ophthalmosauria being used to unite these two groups.