Merro Glastanan

Merro Riac was the King of the White Mountains that initially swore the oath to Isildur when Gondor and Arnor was first founded. It is unknown if he returned as an undead as the curse of Isildur effected the entire mountain. It is possible that Merro was resurrected as an undead with his son and stood next to their grandson, Morthec Gruan