Nahar was the horse of Oromë the Vala. Nahar was said to be as brilliant as new snow in daylight, and as glimmering as silver in the moonlight.
Oromë upon Nahar, hunting evil creatures - by Kip Rasmussen
Before the elves awoke in Middle-earth, Oromë rode Nahar through its great forests. After the awakening of the elves, it was said that if they strayed too far from their encampment, they risked being captured by a strange rider. This was one of Melkor's schemes. The elves thought that a captured elf would be brought to Utumno and tortured. One day, as Oromë was riding through the forest, he came upon the elves. He, realizing the elves had awakened, urged them to journey to Valinor. At first, they feared this strange being, as they believed him to be the rider that would lead them to torment and death; however, Ingwë, Finwë, and Elwë (who would later become Elu Thingol, king of Doriath) rode with Oromë back to Valinor [1] It could be from Nahar that the Mearas were descended this would mean that Felaróf would be his descendant and Shadowfax would be his distant descendant.