List of heroes revealed in this thread with links to English wikis, since not everyone is familiar with every Blizzard Games. Note that this not an official release list, some of the following heroes may not make it into the game.
- Deathwing - Human Form. One of the five Dragon Aspects in the Warcraft Universe, primary antagonist of WoW:Cataclysm. Deceased lore-wise.
- Moira Thaurissan. Daughter of King Magni Bronzebeard, Queen Regent of Ironforge. Apparently in the novel Quest for Pandaria Moira felt insulted by how rude Li Li is.
- Ragnaros. Fire Elemental Lord, allied to Al'Akir (Wind Elemental Lord) and Deathwing to purge all life from Azeroth. Deceased lore-wise.
- Gul'dan. First Orc Warlock, responsible for the enslavement of his people to the demons. Very important Orc character in Warcraft's lore. Deceased lore-wise. DotA character: Warlock.
- Kil'jaeden. Eredar Demon Lord, leader of the Burning Legion. Also very important character in Warcraft's lore.
- Magni Bronzebeard. Former King of Khaz Modan and father of Moira Thaurissan. Turned into diamond in an attempt to commune with the Earth to protect his people from the Cataclysm. Deceased (?) lore-wise.
- Grommash Hellscream. Former chieftain of the Warsong Clan, Thrall's best friend and father of Garrosh. Cursed by the blood of Mannoroth like most of his kin, but ends up sacrificing himself to defeat the demon lord and free his people. Central character in Warcraft 3. Deceased lore-wise. DotA character: Axe.
- Maiev Shadowsong. Night Elf Warden, jailor and slayer of Illidan. Driven mad by her lack of purpose with Illidan's death, she became the aspect of Vengeance. DotA Character: Phantom Assassin.
- Azshara. Queen of the Naga, Empress of Nazjatar, former ruler of the Kaldorei (Night Elves). Said to be the greatest Mage ever to live.
- Shandris Feathermoon. Adoptive daughter of Tyrande and Malfurion, "battle sister" with Jaina, general of the Night Elf Sentinels (Tyrande's successor).
- Brann Bronzebeard. Younger brother of Magni and Muradin, considered as one of the greatest explorers of Azeroth. Mentor of Harrison Jones.
- Jaina Proudmoore. Daughter of Grand Admiral Daelin Proudmoore, student of Archmage Antonidas, Leader of the Kirin Tor and ruler of Dalaran. Most powerful human sorceress alive, she came to intensely hate the Horde after Garrosh destroyed Theramore (wrong move, asshole). DotA character: Crystal Maiden.
- Samuro - Blademaster. Our beloved Blademaster in Warcraft 3. Not much on the lore side here. DotA character: Juggernaut.
- Kael'thas Sunstrider. Prince of Quel'Thalas, Lord of the Blood Elves and last of the Sundstrider Dynasty. Attempted to summon Kil'jaeden through the Sunwell, but failed. Deceased lore-wise. DotA character: Invoker.
- Sylvanas Windrunner. Former High Elf and Ruler of the Forsaken. She was turned into a banshee by Arthas Menethil (whom she despises). DotA character: Drow Ranger.
- Rexxar. Champion of the Horde, Half-Ogre Half-Orc Beastmaster of the Mok'Nathal Clan. Roams the lands with Misha, Spirit, Huffer and Leokk. DotA character: Beastmaster.
- King Varian Wrynn. Also known as Lo'Gosh. King of Stormwind, High King of the Grand Alliance and father of Anduin. Former companion of arms of Broll and Valeera (watch. your. back).
- Gelbin Mekkatorque. High Tinker of Gnomeregan. Crazy little dude. No, seriously. He has a weapon called Wrenchcalibur.
- Garrosh Hellscream. Former Warchief of the Horde, succeeded by Vol'Jin after the Siege of Ogrimmar. Primary antagonist of WoW:Mist of Pandaria. Huge asshole with extreme lust for power. Warning: Article contains spoilers on WoW:Warlords of Draenor.
- Cho'Gall. First of the Ogre-Magi, Chieftain of the Twilight's Hammer Clan. Allied with Deathwing. Deceased lore-wise. DotA Character: Ogre Magi (duh).
- Zul'jin. Warlord of the Amani Forest Troll, mortal enemy of the High Elves. Deceased lore-wise.
- Aggra. Thrall's wife and former shaman mentor. Not much more about her.
- Lady Vashj. Ruler of Illidan's Naga, servant of Azshara. Killed in WoW:Burning Crusade. DotA Character: Medusa.
- Thrall. Former Warchief of the Horde, leader of the Earthen Ring. Central character in Warcraft's lore, there is just too much to say about him.
- Cenarius. Lord of the Forest, one of the most powerful and influential demigods of Azeroth. Son of Malorne and Elune. Central character in Warcraft's lore. DotA character: Leshrac.
- Sapper. Not really a character per se, goblin sappers are just famous for blowing stuff up. DotA character: Techies.
- Dehaka. Primal Zerg Pack Leader from Zerus (Zerg's birth place). Joined Kerrigan as he perceived her as the "Strongest Zerg".
- Horace Warfield. Former Terran Commander in chief of the Dominion Armed Force. Killed by Kerrigan on Char as he stayed behind after ordering the evacuation of his troops.
- Valerian Mengsk. Current emperor of the Terran Dominion, succeeding his father Arcturus Mengsk. Allied with Raynor to take down his father and works on rebuilding the Dominion by trying to eliminate corruption and abolishing forced military conscription and slave labor (good guy).
- Tosh. Everyone's favorite space Rasta. Powerful and mysterious Spectre who joined Raynor in his campaign against Mengsk. Former teammate of Nova, depending on the choice of the player Nova might end up killing him in SC2:Wings of Liberty.
- Fenix. Courageous and mighty Protoss Zealot (and the Dragoon) who allied with Raynor during SC1:Broodwar. Ultimately betrayed by Kerrigan, Fenix fell to the swarm and Raynor vowed vengeance against her (Raynor and Fenix seemed to be very close comrade in arms, with Fenix not being as arrogant as other Protoss).
- Artanis. Tassadar's successor, this "young" (262 years) Protoss is now the Protoss Executor. I don't remember much about him though, so feel free to read the article for more information.
- Mengsk (Arcturus). Valerian's father and dictator, he orchestrated the downfall of the Terran Confederacy during the Great War. Killed by Kerrigan.
- Overmind. Former leader of the Zerg Swarm (preceding Kerigan), created by the Xel'Naga on Zerus to guide the Zerg into merging with the Protoss. Destroyed by Tassadar.
- Leoric - Skeleton King. Former Monarch of Khanduras, corrupted by Diablo. Adventurers' favorite punching bag. DotA Character: Skeleton King (Wraith king)
- Butcher. The Butcher... A scary, lethal encounter in Diablo I who reappears in Diablo III. Final Boss of Act I.
- Lost Vikings. Never played it, can't say much about that.