Warning: SPOILERS for Guardians of the Galaxy #2
Marvel Comics is making huge changes to a classic Avenger in the recently-relaunched Guardians of the Galaxy series, presenting a whole new take on Thanos' brother, Starfox. In more ways than one, Starfox barely resembles the character he once was.
Though far from a household name, Starfox has strong ties to three Marvel properties--the Avengers, Thanos, and the Eternals--which makes him an important character in the Marvel Universe. In a way, Starfox ties all three of them together, which could be one reason why he make his live-action debut sooner than later in the MCU (as certain details about The Eternals movie have suggested that Starfox could appear).
The first issue of the rebooted Guardians of the Galaxy deals with the fallout of Thanos' death. In front of a gathering of cosmic superheroes, Starfox reads his brother's last will and testament, which reveals a sinister plan for Thanos to be resurrected in a new body. No one knows for sure who this could be, but Starfox has come prepared for every possibility.
Starfox comes up with a list of potential candidates for Thanos' new host... and determines that they all have to die, with the first target being Gamora. Before any plan can be put into motion, their meeting place is attacked by the Black Order. Guardians of the Galaxy #2 reveals that Starfox is at least partially paralyzed and his face is horribly scarred, giving him an appearance reminiscent of Batman villain Two-Face. The the similarities between Starfox and Two-Face don't end there. In Batman comics, Two-Face was a well-respected district attorney who went down a dark and murderous path after his face was disfigured. Marvel seems to be doing something similar with Starfox.
It should be noted that Starfox has never been without his flaws. His ability to affect emotions and his adulterous ways have earned him the dislike of many characters--and fans--but he has always been one of the good guys. Starfox never operated in morally grey areas like Wolverine, Punisher, or Deadpool. In most stories, Starfox is portrayed as having the personality of a playboy who loves looking for adventure.
This is why Starfox's sudden willingness to murder innocent people in an effort to "guard this galaxy" draws comparisons to Two-Face. The main thing that sets them apart, however, is their motivations. Two-Face became evil because of what happened to him. As for Starfox, though, the reason isn't clear, and Marvel has yet to provide an explanation.
Guardians of the Galaxy #2 is on sale now from Marvel Comics.