Haro

"As battle was joined, the earth-shattering advance of the Tall Men's chariots smashed through the center of the Dothraki horde, the spinning blades on their wheels slicing through the legs of the Dothraki horses. When one khal went down before them, cut to pieces and trampled, his khalasar broke and fled."

- Jorah Mormont

Khal Haro is an unseen character in Game of Thrones. He is not expected to appear in the series, being long dead when it begins.

History
Khal Haro was one of four khals who fought in what later became known as the Field of Crows. He was killed by being cut to pieces and trampled, causing his khalasar to break and flee.

In the books
In the A Song of Ice and Fire novels, Khal Haro was one of four khals who fought in the Field of Crows, with the others being Qano, Loso, and Zhako. He died in the same manner described in "The Dothraki".