Trilophosaurus (Greek for "lizard with three ridges") is a lizard-like trilophosaurid allokotosaur known from the Late Triassic of North America.

Trilophosaurus had a short, unusually heavily built skull, equipped with massive, broad flattened cheek teeth with sharp shearing surfaces for cutting up tough plant material.

Teeth are absent from the premaxilla and front of the lower jaw, which in life were probably equipped with a horny beak.

Trilophosaurus is traditionally thought to include two valid species: the typical T. buettneri and the more robust T. jacobsi.

In 1993, paleontologists Hans-Dieter Sues and Paul E. Olsen reassigned T. jacobsi, as well as two additional trilophosaurids (Tricuspisaurus and Variodens), to Procolophonidae based on similarities between its tricuspid teeth and those of the newly described procolophonid Xenodiphyodon.