Roheryn

The horse of Aragorn, given to him as a gift by Arwen his betrothed, and so named Roheryn, the 'horse of the Lady'. The horses of the Northern Dúnedain in general were said to be notably strong and used to hard terrain, though - as a gift from the daughter of Elrond - Roheryn was perhaps of different stock to the rough horses bred by the Dúnedain themselves.

When Aragorn went south with the Company of the Ring, he left Roheryn behind in the North. Some time later, a band of Aragorn's Rangers rode into the South to join their Chieftain, and they brought Roheryn with them. After they met in Rohan, Aragorn took Roheryn as his steed, and on that horse he made his way through the Paths of the Dead, and then on through the southern fiefs of Gondor to Pelargir. There Aragorn defeated the Corsairs and took their ships, and then sailed away to join the Battle of the Pelennor Fields.

The capture of the Corsairs' ships is the last moment where we see Aragorn definitively mounted on Roheryn, and after this point the horse's name is not mentioned again. Aragorn does not seem to have taken his horse aboard the ships with him (at least, when Aragorn meets Éomer in the battle, soon after disembarking, he is on foot). Perhaps he left Roheryn with Angbor of Lamedon, who set out to follow the land route from Pelargir to Minas Tirith after the ships had sailed. Angbor was not expected to reach the City before Aragorn led the Captains of the West to the Gate of Mordor, and so - if this conjecture is correct - he could not have ridden Roheryn on that journey. Perhaps the most plausible outcome would be that his horse was awaiting Aragorn, safely stabled in Minas Tirith, when he returned from the victory over Sauron.

We might expect that Aragorn would have later ridden Roheryn in the funeral procession of Théoden, especially given that Arwen - who had gifted him the horse - rode beside him on that journey. On the other hand, certain of the mounts in that riding are named (specifically, Shadowfax and Arod) and it is notable, perhaps, that Roheryn's name is not among these. Ultimately, Roheryn's fate after Pelargir remains unknown.