Regisaurus ("Rex's lizard", named after Francis Rex Parrington) is an extinct genus of small carnivorous therocephalian.

[1] It was a rather derived baurioid, with a robust skull, short tail, long limbs and relatively large canines.

It had six incisor teeth in each side of the jaw, whereas other baurioids had less.

[2] It was probably carnivorous, and ate insects and small vertebrates Regisaurus was discovered in 1964 by James W. Kitching and it was named in 1972 by C. H. Mendrez.

[4][5] Below is a cladogram modified from Sidor (2001) and Huttenlocker (2009):[6][7] Ictidosuchops rubidgei Ictidosuchus primaevus Ictidosuchoides longiceps Regisaurus jacobi Urumchia lii NHCC LB44 (Unnamed Zambian karenitid) Karenites ornamentatus Lycideops longiceps Choerosaurus dejageri Tetracynodon tenuis Tetracynodon darti Scaloposaurus constrictus Ericiolacerta parva Silphedosuchus orenburgensis Nothogomphodon danilovi Hazhenia concava Ordosiodon youngi Bauria cynops Antecosuchus ochevi Microgomphodon oligocynus Traversodontoides wangwuensis