Damien Darhk

Damien Darhk is the leader of H.I.V.E., and a former member of the League of Assassins. He was Ra's al Ghul's rival as heir to the demon, as well as his best friend.

Heir to the Demon
At one point, Damien Darhk and an unnamed man were horsemen of Ra's al Ghul. The former thought himself worthy of taking the mantle, though the latter was the chosen one. Damien was to be killed but managed to escape with waters of the Lazarus Pit.

H.I.V.E.
According to Ra's, Damien currently commands a "hive of followers" around the world.

Abilities

 * Peak of human physical condition: As a highly skilled assassin, Damien is in top physical condition.
 * League of Assassins training: Damien has gone through the training all League members do. He likely possesses skills with a variety of other melee weapons such as swords.
 * Master hand-to-hand combatant/Martial artist: As the leader of H.I.V.E. and a former member of the League of Assassins, Damien is a master in hand-to-hand combat and martial arts.
 * Master swordsman: As the leader of H.I.V.E. and a former member of the League of Assassins, Damien is a master swordsman.

Season 3

 * (mentioned)

Behind the scenes

 * In the DC comics, Damien Darhk has a connection with H.I.V.E. and a major target for the CIA and FBI.
 * In the DC comics, a character named Doctor Darkk was the first person other than Ra's al Ghul to lead the League of Assassins.
 * Ironically, Doctor Darrk had a falling out with Ra's al Ghul, similar to the show's version of Damien Darhk, making it possible that the character is actually an amalgamation of the DC comic versions of Damien Darhk and Doctor Darrk.