Ischyrodon is a dubious genus of large, carnivorous marine reptile belonging to the Pliosauroidea, a clade of short-necked plesiosaurs and it is known from the Middle Jurassic (Callovian) of Wölflinswil, Switzerland. The type species is I. meriani, and was previously listed as a synonym of Liopleurodon ferox.
Ischyrodon was named in 1838 and described in 1856 by Hermann von Meyer. Lambert Beverly Tarlo noted the possibility of it pertaining to Liopleurodon in 1960. A 2022 study by Daniel Madzia and colleagues noted that while the tooth likely came from Liopleurodon or something similar, there was too little information available to make a confident assignment, so they treated Ischyrodon as a nomen dubium and did not synonymise Ischyrodon with Liopleurodon.