Arod

From Tolkien Gateway

Arod was a light horse of Rohan, whose name means simply 'swift' from Old English. After the loss of his original rider, Arod was given to Legolas by Éomer, and he served his new rider faithfully throughout the War of the Ring. For much of this time, Arod carried two riders, since Legolas was often accompanied by his friend Gimli.

Portrayal in adaptations

In The Lord of the Rings: The Two Towers and The Return of the King, Arod is played by a white stallion named Percy. According to Orlando Bloom, it was the friendliest horse on the set.