Giant Horse (5e Creature)
From D&D Wiki
Huge beast, unaligned
Bulky Frame. Bred for size instead of speed, the giant horse cannot sprint like smaller horses naturally can. It is unable to take the Dash action.
Hooves. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 12 (3d4 + 5) bludgeoning damage.
This creature's ancestry includes more mundane horses that have been bred over millenia purely for size and strength by giants and other unusually large humanoids. Their unusually large size enables them to be used as mounts by giants or humanoids of Large size. They are normally kept domesticated in the domains of these tamers, but tales tell of a few of them riding through open plains.
A tamed giant horse will typically go for hundreds of gold pieces (roughly 1,000 gp), and in practice is equivalent to an uncommon magic item.