Due to the length of time between the dates of his known prophecies (at least 100 years), it is likely that Malbeth was of Númenórean descent, although this isn't explicitly stated.
Last King of Arthedain
- "Arvedui you shall call him, for he will be the last in Arthedain. Though a choice will come to the Dúnedain, and if they take the one that seems less hopeful, then your son will change his name and become king of a great realm. If not, then much sorrow and many lives of men shall pass, until the Dúnedain arise and are united again."
- ― Appendix A
In 1975 Arvedui was forced north by the forces of Angmar to the Ice Bay of Forochel to seek the help of the Lossoth. Círdan, hearing of Arvedui's plight from Arvedui's son Aranarth sent a ship to rescue him in the spring of that year. The Snowmen advised the king not to board the ship as they could smell danger in the air, they suggested that the king should wait until the summer when the Witch King's power isn't so strong. Arvedui did not heed the advise and he perished when the ship broke upon some ice in a severe storm; thus, Malbeth's prophecy was fulfilled.
Paths of the Dead
Malbeth's second prophecy was in the days of the Arvedui (ruled T.A. 1964 -1974), the last king of Arthedain, in which he foretold Aragorn's passage through the Paths of the Dead even though the event was over a thousand years in the future:
- "Over the land there lies a long shadow,
westward reaching wings of darkness.
The Tower trembles; to the tombs of kings
doom approaches. The Dead awaken;
for the hour is come for the oathbreakers:
at the Stone of Erech they shall stand again
and hear there a horn in the hills ringing.
Whose shall the horn be? Who shall call them
from the grey twilight, the forgotten people?
The heir of him to whom the oath they swore.
From the North shall he come, need shall drive him:
he shall pass the Door to the Paths of the Dead."
- ― The Return of the King, "The Passing of the Grey Company"
This prophecy was also fulfilled in 3019 during the War of the Ring when Aragorn (sixteenth Chieftain of the Dúnedain) learnt from the palantír that Gondor was being threatened from the south by a fleet of Corsairs from Umbar. He needed a route to get to them in haste, and Elrond's message ("Bid Aragorn remember the words of the seer, and the Paths of the Dead") told him how.
Aragorn (with Legolas, Gimli and the Grey Company) travelled through the Paths of the Dead to the Stone of Erech where Aragorn blew a horm to summon the Oathbreakers. He told them he was Isildur's heir and so they fulfilled their oath and defeated the Corsairs which helped Gondor win the Battle of Pelennor Fields.
Malbeth's name is Sindarin for "Golden Word" from mal meaning "gold", and peth (becoming lenited to beth) meaning "word, voice".