Yaks are large, shaggy-haired bovines native to the high altitudes of the Himalayas and Tibetan Plateau. They are known for their thick, long hair that helps them survive in cold climates.
Other possibilities could be:
* Bison: Both American bison and European bison have shaggy coats, although they are not technically "wild" anymore.
* Aurochs: The extinct wild ancestor of domestic cattle, known for its thick coat.
Do you have any more information about the ox you're thinking of, like where it lives or what it looks like? That could help me narrow it down!