Brachypterygius (meaning ″wide wing/paddle″ in Greek) is an extinct genus of platypterygiine ophthalmosaurid ichthyosaur known from the Late Jurassic of England. The type species was originally described and named as Ichthyosaurus extremus by Boulenger in 1904. Brachypterygius was named by Huene in 1922 for the width and shortness of the forepaddle, and the type species is therefore Brachypterygius extremus. The holotype of B. extremus was originally thought to be from the Lias Group of Bath, UK, but other specimens suggest it more likely came from the Kimmeridgian Kimmeridge Clay (Late Jurassic) of Kimmeridge Bay, Dorset, UK.