Undead Alliance

"After the Haunted Estate is destroyed, the DBR Corporation, the Undead Kingdom of Deyja, and the Undead Empire formed a terrifying three-state alliance called the Undead Alliance, and thus they started to avenge the Haunted Estate's destruction."

--Su Ji-Hoon, The Haunting Aftermath

The Undead Alliance is an alliance between the DBR Corporation (The House of the Dead), the Undead Kingdom of Deyja (The Heroes of Might and Magic III) and the Undead Empire (World of Warcraft).