Cable (Nathan Christopher Charles Summers) is a fictional character appearing in American comic books published by Marvel Comics, commonly in association with X-Force and the X-Men. The child Nathan first appeared as a newborn infant in Uncanny X-Men #201 (January 1986) created by writer Chris Claremont, while the adult warrior Cable was created by writer Louise Simonson and artist/co-writer Rob Liefeld, and first appeared in The New Mutants #87 (March 1990). Initially, Cable's origin was undecided and he was assumed to be a separate character. It was later decided that he was actually an older version of the child Nathan, having later become a time traveler.
Nathan Summers is the biological son of the X-Men member Cyclops (Scott Summers) and his first wife Madelyne Pryor (Jean Grey's clone). This makes him the "half"-brother of Rachel Summers (a child of Scott and Jean from an alternate timeline who later comes to the mainstream Marvel timeline) and Nate Grey (a clone created from the combined DNA of Scott and Jean). The mutant terrorist Stryfe is a clone of Cable and one of his deadliest enemies. Born in the present-day, Nathan was infected with a deadly techno-organic virus while still an infant. He was sent into a possible future timeline where he could be treated and live his life. In this future world, Nathan grew into the warrior Cable and became an enemy of the villain Apocalypse. He later returned to the present-day era, initially arriving some years before his own birth. Since making his home in the modern era, he has worked alongside the X-Men (including Cyclops and Jean Grey) and reformed the New Mutants group into the original X-Force. He had frequent battles against the near-invincible assassin Deadpool, who later became an on-again, off-again ally for years. In the 2018 Extermination mini-series, Cable was killed and replaced by a younger, time-displaced version of himself who decided that the older one didn't do a good enough job. This younger Cable (sometimes called Kid Cable) is still operating today.
Source: Wikipedia, "[en.wikipedia.org/wiki/Cable_%28character%29 Cable (character)]", available under the CC-BY-SA License.