Admiral Thomas Perry. He betrayed The Union to give the Krill and Moclan the weapon that can destroy Kaylon because the Union considered the weapon as a last resort for they deemed it to be a weapon of genocide, they believe the Kaylons, despite being artificial intelligence have the capacity of change. But Thomas Perry doesn't see this and wants to destroy the Kaylon.

We can see here that this is one of a captain's traits that exists within, even after being promoted to admiral. One of the examples in Star Trek is Captain Maxwell, a decorated captain who destroyed Cardassian ships and outposts because he believed the Cardassians were re-arming and re-equipping themselves, having himself go rogue until his arrest.

Admiral Perry here is an example of such a captain who managed to be promoted to admiral. And when he faced the dilemma that we've seen in Star Trek, that was the path he took. That's whats awesome about the admirals in The Orville. They're not politicians, they're former captains and leaders each in their own way.

P.S. I keep referring to him as Michael throughout the 3rd season because he's such an actor in the sitcom "The Good Place"