Teron Gorefiend was an Orc warlock and member of the Shadow Council until he was killed by Orgrim Doomhammer and later reincarnated in the body of a knight of Azeroth as one of Gul’dan’s Death Knights. Following the defeat of the Horde in the Second War, Gorefiend took control of the surviving Death Knights who had remained on Azeroth (some others had already established on Draenor before the destruction of the Dark Portal). Gorefiend aligned himself with Ner’zhul hoping to use one of his portals to invade a world for the Death Knights alone to conquer. His fate remains unknown, but he was possibly killed (his body destroyed) when an elite group of the Alliance Expedition on Draenor attacked Fortress Shadowmoon.

Teron Gorefiend appears in an elite quest chain in Shadowmoon Valley in Outland. Gorefiend also appears in the Black Temple raid instance as one of the bosses.

A brief video of World of Warcraft: The Burning Crusade (Beta) shows an ephemereal Teron Gorefiend being subdued and banished by dark casters, only to escape them and ride away.

Appears in Warcraft II: Beyond the Dark Portal
Appears in World of Warcraft: The Burning Crusade

Tagar Spinebreaker was the leader of the cannibalistic Bonechewer Clan. Tagar Spinebreaker garbs himself in the innards of his enemies; those which he does not devour himself. Tagar is ruthless and bloodthirsty, craving only the heat of battle above all else. The Bonechewers stayed in Draenor during the First Crossing, but when the Second Crossing was imminent, the Bonechewers were attacked by the Shadow Moon Clan, for one of their captains possessed the Skull of Gul’dan as a trophy. Their camp was obliterated and the skull reclaimed. Soon after, Tagar, along with Fenris of the Thunderlords, decided to sojourn into Azeroth, rising to the challenge and succeeding where their predecessors failed. Ner’zhul refused their suggestions, and their Clans were slaughtered.

Mentioned in Warcraft II: Beyond the Dark Portal
Found in World of Warcraft: Burning Crusade Hellfire Peninsula.

Shandris Feathermoon was orphaned in the first war against the Burning Legion, and was taken care of by Tyrande Whisperwind. During the events surrounding Warcraft III, she was a great Sentinel leader and one of Tyrande’s most trusted lieutenants. She is considered the best archer in Azeroth. She now resides as leader of the Feathermoon Stronghold in the region of Feralas.

Appears in Warcraft III: Reign of Chaos
Appears in World of Warcraft
Appears in the novelization Warcraft: War of the Ancients trilogy

Sargeras, a bronze-skinned Vanir Titan, used to be the champion of the Pantheon. Once he was sent to deal with several demonic races. He managed to defeat them and imprison them. But due to the corruption of these demons, he went insane. He released the demons from their prisons, who were quick to ally with the Dark Titan, bowing before his vast power.

Sargeras began invading worlds, becoming the leader and creator of the Burning Legion. His mortal avatar appeared before, and was killed by, the Guardian Aegwynn, but not before possessing her son Medivh. His spirit lay dormant within the young man for many years, corrupting him with subtle manipulations that culminated in the opening of the Dark Portal which brought the Orcs into Azeroth.

Eventually, Medivh was killed and Sargeras’ spirit was exorcised by the mage Khadgar, the Knight Anduin Lothar (trainer of Uther the Lightbringer, founder of the Paladins of the Silver Hand) and the half-Orc Garona. What is left of the Dark Titan is currently in the Twisting Nether, completely incapable of doing anything, due to his lack of a physical form. If he were able to once more make himself physically manifest, he would arguably be the most powerful being in the Warcraft universe.

Appears in the novelization Warcraft: The Last Guardian.
Appears in the novelization Warcraft: War of the Ancients trilogy
Appears in Warcraft III: The Frozen Throne

Rhonin is a powerful human mage of the Kirin Tor, and the hero who saved Alexstrasza the Dragon Queen. By destroying the Demon Soul and restoring the other Aspects to their original power. Also played a role in stopping the first invasion by the Burning Legion after being transported back in time, thousands of years before the Orcs invaded Azeroth. Husband of Vereesa Windrunner and father to their twins.

Appears in the novel Warcraft: Day of the Dragon
Appears in the Warcraft: War of the Ancients trilogy.