Rockhoof is a very large Earth Pony, the largest Earth Pony presented in the series. His fur is a pale, light cyan blue, his eyes greyish blue, and his mane and tail both gamboge with a gold stripe running through them. He also sports a beard, moustache combo, and a bit of his mane is shown braided. Prior to the event with the volcano, he is shown as very weak and scrawny.
His outfit consists of brown leather clothes on his chest, and legs, with a metal plate tied around his chest, and a headband on his forehead and one on the end of his tail.
Rockhoof grew up in a seaside village near a gigantic volcano, which was guarded by an elite group of guards ponies, the Mighty Helm. Described by Applejack, Rockhoof always wanted to be in the helm but was too weak to do so. One day, he was the first to find the volcano in his village erupting, and when seeing no one wanting to leave, he began to make a trench in order to save his village. Just before the lava could pour onto him, a magical surge made his visibly, and physically stronger. Once that happened, Rockhoof used his new strength to finish the trench and as such, not only saved his village, but also earning a place within the mighty helm.
While with the Pillars of Equestria, he and the others manage to banish the The Dazzlings from Equestria towards Earth. He was praised for his feats by the locals along with the other members of the Pillars. When he and the others were confronted by the Pony of Shadows, he was banished into Limbo in a self-sacrifice with everyone else to keep the Pony of Shadows down.
He returns to present day after the Harmony Gems bring them back, and he joins the others in fighting the Pony of shadows to put him back into Limbo.
My Little Universe II
He briefly appears as part of the Pillars during the three-part finale, fighting Grogar's Army in the Realm of Corners.