Gul'dan

Gul'dan, known also as "Darkness Incarnate" and "The Destroyer of Dreams", is a principal antagonist from the Warcraft universe. Originally a shaman, he became the first orcish warlock as well as the de facto founder of the Orcish Horde. Abandoning the ways of shamanism and betraying both his people and his mentor to the demonlord Kil'jaeden for personal gain and power, Gul'dan was directly responsible for the orcs' fall to demonic enslavement as well as for the Horde's invasion of Azeroth. Tutored by the lord of the Burning Legion, he became the founder and master of the Shadow Council as well as the creator of the necromantic terrors known as death knights. Gul'dan is considered by many to have been the most cunning and powerful mortal warlock to ever have existed. After his death, his skull became a powerful arcane relic until its powers were absorbed by Illidan Stormrage.

Alternate Timeline
In the alternate timeline created by Garrosh Hellscream, Gul'dan still offered the orcish clans the blood of Mannorath to the orcish clans of Draenor. Garrosh's father Grommash Hellscream was to take the first drink, but Garrosh had informed him that doing so would lead to the orcs enslavement by the Burning Legion. When Grom rejected the offering, Mannorath himself appeared, angered by the rejection of his 'gift'. However, the orcs suddenly attacked the pit lord with the technology Garrosh had brought with him from the present. After being blasted by an iron star, Mannorath met his end when Grom plunged Gorehowl into his forehead. As the pit lord's body exploded, Garrosh pushed Grom out of harm's way, saving him from what had claimed his life in the original timeline.

With the Legion's plot foiled, a cowering Gul'dan excalimed that this was not the orc's destiny, but Garrosh simply told him that times changed. The warlock's plans to invade Azeroth were repurposed to suit the new Iron Horde, and Gu'ldan, Cho'gall and Teron'gor were captured and forced to power the Dark Portal built to link the two timelines.

As adventurers fought against the Iron Horde, Khadgar set his sights on Gul'dan and set out to create a ring powerful by sending the garrison commander to obtain mystical items and to hopefully destroy Gul'dan.

After adventurers slay crippled the Blackrock foundry and killed Blackhand, The Iron Horde was heavily weakened. The garrison commander, with the aid of Garona Halforcen, watch as Gul'dan again offers the blood of Mannoroth to Grommash and showed Grommash Gorehowl, telling him about Garrosh's death. Grommash, saddened by Garrosh's death and bound by honor still refuses and is defeated by Gul'dan in battle. Killrogg takes the blood and is corrupted while Gul'dan takes the rest of the Iron Horde.

Gul'dan takes control of the Hellfire Citadel for the Burning Legion's operations. He muster Archimonde into Draenor for the final battle. Overcomed, Archimonde sent Gul'dan into the Twisting Nether for failing the Legion.

Gul'dan was subsequently sent to Azeroth in order to open the gateway for another Burning Legion invasion of Azeroth. He located the Tomb of Sargeras, where Illidan Stormrage's body and soul were being kept and freed the Betrayer from his prison.

Personality
Gul’dan possesses an unquenchable thirst for power and a ruthless personality. Equally willing to manipulate friend and foe alike, he constantly tries to better his station in life through any means possible. Even though Gul’dan constantly tends to be embroiled in many different plots and schemes, his overarching goal is always to discover the location of the Tomb of Sargeras and to claim the dark titan’s powers for himself. Nothing else matters in comparison to this quest, and Gul’dan is willing to betray his own people and sacrifice his closest friends to achieve it.

Gul’dan can only be trusted to do what is in his own best interests. He often freely offers wealth to people in exchange for clues or information that might be useful, and then has them killed and reclaims his payment. Gul’dan only truly trusts people who are like himself — those who are openly ambitious and who will do anything to improve their lot in life. He feels that those people can be most easily predicted and manipulated through offers of wealth or prestige. It is the people who serve higher moral or religious powers that he fears. They are often resistant to his lures, and in Gul’dan’s eyes can never be completely trusted or relied upon. Because of this, he tends to associate most easily with mages, sorcerers, rogues and scouts and dislikes druids, priests and paladins. His allegiance is with the Horde, and he is openly hostile to members of the Alliance races unless they are key to something Gul’dan desires.