3. Captain Forrest
This might seem like an odd choice from the Mirror universe, but Captain Maximilian Forrest is a complicated character when compared to the Prime counterpart, who is a flag officer and advises Archer on some of the NX-01's early missions. He's also a close friend of Jonathan Archer.
In the Mirror Universe, Archer is Forrest's first officer; however, there is little trust between them. While Forrest is not as cruel as Phlox or as cunning as Hoshi Sato, who aligns herself with whoever ends up in charge, Forrest makes the mistake of believing that Archer has no real ambition, which makes him an effective first officer.
Later, as Forrest's mistrust of Archer grows, he orders T'Pol to assassinate him during an away mission to the newly-discovered USS Defiant, as he's still angry about Archer's earlier betrayal. Ultimately, he shows compassion for his other crew members, as he stays onboard the ISS Enterprise as it's destroyed by a Tholian attack to give them time to escape. Unfortunately, he and most of those who try to escape are eliminated by the Tholians.