If you've ever looked at a card from Magic: The Gathering, you most likely have seen this name. If you've played it, you have to know. For those who have read the books, you never stop hearing this name.
Born in the country of Argive, was sent to the desert to study with Tocasia when his father grew ill.
He had a brother, Mishra, though they never did quite get along. When they acquired powerful artifacts, the Mightstone and the Weakstone, their differences grew stronger. Urza had the Mightstone, while his brother had the Weakstone.
Almost sixty years after they first found the stones, their battles had raveged the land and ended up destroying most everything. During the early years, Urza attracted an apprentice named Tawnos. Mishra also attracted an apprentice, Ashnod. In the final battle, Urza used another artifact, the Cylex, to destroy what was left of his brother and to attempt to repair the damage they had done.
This final action also fused the two stones into Urza's spirit, turning him into a planeswalker, one who can move through different planes of existance.
It is important to note that Urza and Mishra were not wizards, as the game seems to portray them as. They were artificers, and spells were unheard of until near the end of the book.
The Brothers' War by Jeff Grubb
I haven't finished the series, so if someone wants to finish the tale, please do. Otherwise when I get to it I'll keep adding.