Agassizodus is an extinct genus of eugeneodont holocephalian fish that lived during the Carboniferous Period. It belongs to the family Helicoprionidae, which is sometimes called Agassizodontidae. Like other members of its family, it possessed a symphyseal tooth whorl, which was likely present at the tip of the lower jaw and associated with lateral crushing tooth plates. The type species, A. variabilis, was originally named Lophodus variabilis until the name "Lophodus" was determined to be preoccupied.