King of the Dead
From Tolkien Gateway
The King of the Dead was the king of the oath-breaking Men of the White Mountains, who swore allegiance to Isildur in the War of the Last Alliance. For breaking his oath, he and his people were cursed to walk the Paths of the Dead as the Dead Men until they could redeem themselves, which they achieved by aiding Isildur's heir Aragorn in the War of the Ring.
