Warmonger

Warmonger is, as far as most bots know, a Decepticon from the Marvel portion of the Generation 1 continuity family.
An Autobot? Me? This must be one of your Decepticon jokes.

Warmonger is not really a Decepticon! He's actually an Autobot working undercover. And what a fortuitous choice for the job. Heck, his name is Warmonger, and he looks like a conehead. What can go wrong?

Fiction

Marvel Comics continuity

Marvel The Transformers comics

Warmonger appeared exclusively in the UK portion of the Marvel Comics continuity.

In the year 1990, an infiltrator within the Decepticon ranks had freed the captured Hot Rod, Kup, and Blurr. After Hot Rod had been recaptured, Megatron believed this traitor had to be either Warmonger, Octopunch, Stranglehold or Bludgeon, and so he ordered three of the suspects to battle Bludgeon to death. Warmonger got the drop on Bludgeon after the latter had dispatched the other two, but at the critical moment refused to kill him. When Megatron saw this, he correctly concluded that Warmonger was an Autobot, and killed him. Aspects of Evil!