Dunkleosteus

Dunkleostues was a real fish before anyone starts on me.

It's a Armored fish that lived during the late Devonian. They get to about 11ft long with a 2ft long skull. Now it's "teeth" aren't really teeth they technically are "dental plates". Very much like scissors but with it's vice like jaws, it would be able to crush right through the armor plates of the other armored fish of it's time.

(update I finally gave him a name. His name is Donovan)