Hasufel
From Tolkien Gateway
Hasufel was the grey-coated steed of Gárulf of Rohan. After the loss of his master in battle, Hasufel was lent by Éomer to Aragorn when they met in the northern fields of Rohan. The hardy creature saw many adventures, including the Battle of the Hornburg, before Aragorn was brought his own horse, Roheryn, by the Rangers of the North.
