Bahamut (Final Fantasy XV)

Bahamut at first appears to be an ally of Noctis Lucis Caelum in the base storyline of Final Fantasy XV, but is soon revealed to be the true villain of the game's expanded universe.

Personality
Bahamut is protective of the planet, but possesses a ruthless streak, as more clearly evidenced in the bonus content added after release: Final Fantasy XV: Comrades, Final Fantasy XV: Episode Ardyn and Final Fantasy XV -The Dawn Of The Future-. The content released after the main game reveals him to be uncaring toward the individuals who are to play a part in the fate he has spelled for the planet.

Trivia

 * This depiction of Bahamut is the first to be outright evil without any outside influence or another antagonistic character controlling him, in a subversion of his role in the original Final Fantasy appropriate enough(for most fans to think FFXV could be the last numbered game in the series).
 * As with Ardyn, before his reveal to be a legitimately tragic (anti-)villain, Bahamut is one of the few villains to win, at least in the game's original ending. The companion epilogue novel, "The Dawn of the Future", shows a new timeline, branching off from the end of Episode Ardyn, where Bahamut's true nature is exposed before it's too late.
 * His role is similar to Bhunivelze in Lightning Returns: Final Fantasy XIII.