Hro Talak is the main antagonist of the series finale of Justice League, Starcrossed. He didn't look at ethics to protect his people and was willing to sacrifice an entire planet (several planets in fact) in the process. This hardhearted fixation to defeat the Gordanians resulted from Hro Talak having been captured and tortured by the Gordanians at one point, leaving him physically and physiologically scarred. Therefore, while he is undeniably antagonistic, he is closer to a tragic anti-hero, than a villain, as he is driven by determination to protect his people and loved ones. However, he's still not above stepping on or even killing others to achieve his goals.
Hro is a geniunely calm and serious individual. He possesses leadership skills and usually remains charming. However, he can also be violent and aggressive when he's angered, often when he has a good reason to be.
Hro is on a mission to destroy the Earth, but only to save his planet, Thangar. He didn't see any other way out and therefore saw it as the only option. However, he does not take pleasure from it. Therefore he remains noble, but due to valuing his people's lives more than anyone else, he's not above killing anyone else, in order to save them.