Agassizodus is an extinct genus of eugeneodont holocephalian from the Carboniferous.

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 toothplates.

[2] A. variabilis was originally based on tooth fragments from the Pennsylvanian of Illinois, but the authors who named the genus (St. John and Worthen, 1875) also referred a massive jaw from Osage County, Kansas.

The Osage jaw shared some similarities to tooth-whorls from the area, which were later described by Eastman (1902).

[2] Other authors disagree, arguing that the Eastman specimens and the Osage jaw represent neither Agassizodus or Campodus, but rather an entirely new genus.