Cooyoo ("fish" in the Yirandhali language) is an extinct genus of ichthyodectid ray-finned fish known from the Lower Cretaceous. It contains a single species, C. australis, known from the Albian-aged Toolebuc and Allaru Formations of Queensland, Australia. C. australis was originally named by Arthur Smith Woodward as a species of Portheus (now a probable synonym of Xiphactinus) in 1894, which was later amended to Xiphactinus.
