Which 1993 Super NES game introduced Zero as X's ally?

The 1993 Super NES game that introduced Zero as X’s ally is Mega Man X.

Mega Man X is the first game in the Mega Man X series and shifts the setting roughly a century beyond the original games. Its hero, X, is a more advanced robot created by Dr. Light. Zero serves as his partner and mentor, helping him fight Sigma and the Mavericks threatening humanity.

Zero is not the playable protagonist in the original game. He supports X during the story, rescues him during an early encounter with Vile, and later sacrifices himself to help X win their decisive battle. His role established the partnership that became central to later X-series games.

A common mix-up is Mega Man X3, which was the first game in the series to make Zero playable, though with important limitations. Mega Man X2 continues Zero’s story but does not introduce him; the character’s debut is in the original 1993 Mega Man X.