Nothing has been revealed about the origin of the indigenous Australian known only as Gateway before he was forced into service by the Reavers, a band of criminal cyborgs who used Gateway's teleportational abilities to travel from place to place. The Reavers had threatened to destroy a place sacred to his people in a way that would make it impossible to be reconsecrated and would force the spirits of their ancestors to be enslaved by demons and walk forever lost in the spiritual Dreamtime.
It was the Reavers who named the man "Gateway," as his true name is, apparently, known only to himself. Gateway spent virtually all his time sitting atop a rock near the Reavers' headquarters in the Australian outback. The team of superhuman mutants known as the X-Men tracked the Reavers from Hong Kong to their outback base and defeated them in battle. One of the Reavers, Skullbuster, told Gateway he would release him from all vows and obligations to the Reavers if he would use his powers to transport him to safety this one last time. Gateway agreed, and Skullbuster and two other Reavers escaped through a teleportational "gateway" that he created.
After defeating the Reavers, the X-Men took over their headquarters. Gateway began voluntarily using his teleportational powers to transport the X-Men from place to place, with the telepathic X-Man named Psylocke using her mental powers to tell Gateway where they wanted him to send them. Gateway thus became an unofficial member of the team, but he himself remains a mystery even to them.
During his affiliation with the X-Men, Gateway transported the young mutant named Jubilee to their Australian outback base. Gateway later appeared at the campus of the new branch of Professor Charles Xavier's School for Gifted Youngsters at the Massachusetts Academy in western Massachusetts where the members of the young team of mutants known as Generation X received training in the use of their mutant powers. Here, Gateway continued his mysterious meditations, although he did break his silence to utter the name of Penance, a young mutant he had brought to the school. Gateway had been weighed down by guilt for a role he played in the destruction of another group of mutant students, the Hellions, and sought to redeem himself. It was also revealed that Gateway was, at one time, mentor to the young mutant St. Croix twins, Claudette and Nicolette, when they were merged together to impersonate their older sister Monet.
Eventually, Gateway teleported away from the campus, having decided his time with Generation X had come to an end. He later appeared to the renegade "X-Treme X-Men" team after the death of Psylocke, revealing to the X-Man known as Bishop that he was his great-grandfather. Recently, Gateway was assassinated by the Marauders.