Scott Summers was the older of the two sons of Major Christopher Summers, a test pilot in the U.S. Air Force. When Scott was a child, Major Summers flew himself, his wife Katherine, and his sons Scott and Alex back from a vacation in his vintage private plane. The plane was attacked and set ablaze by a scout ship from the alien Shi’ar Empire. Katherine pushed Scott and Alex out the plane door with the only available parachute. The parachute was unable to slow their fall sufficiently to prevent Scott from suffering a head injury on landing (the injury damaged the part of Scott’s brain that would have enabled him to control his optic blasts). The two boys were separated by the authorities: Alex was adopted, but Scott remained comatose in a hospital for a year. Christopher and Katharine were believed dead (actually, they were taken prisoner by the Shi’ar; Katharine soon died but Christopher later became Corsair, leader of the Starjammers, a band of interstellar adventurers). On recovering, Scott was placed in an orphanage in Omaha, Nebraska that was secretly controlled by his future enemy Mister Sinister. Years later, as a teenager, Scott began to suffer from severe headaches and eyestrain. He was sent to an eye specialist in Washington, D.C., who discovered that lenses made of ruby quartz corrected the problem.

While Scott was visiting a large city, his developing mutant power to project optic force beams finally erupted, bursting forth in an uncontrollable blast that demolished a crane, causing it to drop a huge object towards a terrified crowd. Scott saved the crowd by obliterating the object with another blast, but they turned into an angry mob, thinking he had tried to kill them. Scott fled, ultimately escaping on a freight train. Professor Charles Xavier and F.B.I. agent Fred Duncan joined forces in their mutual attempt to find Scott. Meanwhile, a mutant known as Jack O’ Diamonds, and later as the Living Diamond, forced the frightened boy to aid him in his crimes. Xavier rescued Scott from the Living Diamond and enlisted him as the first member of the team of young mutants he would teach in using their powers, the X-Men. As Cyclops Scott soon became deputy leader of the X-Men. He fell in love with his teammate Jean Grey, although his reserve and his worries about the dangers of his optic beams prevented him for years from expressing his feelings to her. When the other original X-Men left the team, Cyclops stayed on as deputy leader of the “new” X-Men.

Shortly afterwards the cosmic entity called the Phoenix Force secretly placed Jean in suspended animation and impersonated her, adopting a form identical to hers. When this Phoenix committed suicide, Scott believed that the real Jean had died and he left the X-Men. Eventually he returned to the team and met and married Madelyne Pryor, a woman who was Jean’s double; he was unaware she was a clone of Jean created by Mister Sinister. Scott and Madelyne had a baby son, named Nathan Christopher, and Scott again left the X-Men.

Subsequently, the real Jean Grey emerged from suspended animation. Scott left his wife and joined with Jean and the other original X-Men in founding a new team, the original X-Factor. Madelyne went insane, developed superhuman powers, and perished in combat with Jean Grey. Later, Apocalypse infected Nathan with a techno-organic virus. To save his life, Scott was forced to allow a time traveling member of the Askani cult to transport Nathan to the 30th century of an alternate future. After Professor Xavier returned from a long sojourn in space with the Starjammers, Cyclops and the other X-Factor members rejoined the X-Men. Ever since then Cyclops has remained with the X-Men, sharing deputy leadership with Storm.

Recently, Scott and Jean were finally married. While they were on their honeymoon, Mother Askani, leader of the Askani cult, drew their spirits two millennia into an alternate future, where they inhabited new bodies. There, as Slym and Redd, they spent years raising young Nathan into his early adolescence. Then Scott and Jean returned to their own time and bodies, and Nathan remained to grow up into his time’s greatest hero, Cable.

Not long after returning to the team, Scott and Jean soon found themselves embroiled in Apocalypse's bid for cosmic power by assembling "The Twelve" - a group of mutants who would determine the fate of their kind that included Scott, Jean, and Cable. They were wired to a machine that would channel their awesome energies into Apocalypse, allowing him to absorb the body of the time-tossed powerful mutant teenager known as X-Man. As his teammates fell around him, a powerless Scott saved X-Man and merged with the would-be conqueror to create a new evil entity. Jean detected Scott's psyche inside Apocalypse and prevented the X-Men from destroying him, however he was presumed dead by most of his teammates. Only Jean and Cable refused to believe Scott had perished. Investigating rumors he was alive, the pair found him in the birthplace of Apocalypse in Akkaba, Egypt, struggling to reassert his mind over the villain's psyche. Ultimately, Jean was able to physically rip Apocalypse's essence from Scott's body using her mental powers, and Cable destroyed it with his own powers.

Scott left for a small period of recuperation, during which he met and reconciled with his father. Afterwards, Scott returned to the X-Men, but his association with Apocalypse had given him a grimmer, more serious personality than ever before. As a result, many of his relationships became strained, including his marriage to Jean. Scott sought the counsel of his teammate Emma Frost and the pair began a psychic affair. When Jean discovered Scott's betrayal, he left the X-Men in order to sort out the mess his life had become. Following the outing of Professor X as a mutant to the world, his school was rechristened the Xavier Institute of Higher Learning and opened its doors to the mutant population at large, training and educating dozens of young new students to help them cope with their burgeoning abilities. After the death of his wife, Scott assumed the position of co-headmaster of the School alongside his new love, Emma.

Cyclops's world was further upset when a mysterious mutant attacked and brought him and Marvel Girl to a secret abandoned facility. Cyclops eventually discovered that the mutant was none other than his brother Gabriel, who had been a student of Moira's that Professor X had sent to rescue Scott from Krakoa. Scott had witnessed the apparent deaths of Gabriel and his teammates; Xavier had mind-wiped him to alleviate the psychic trauma of the event. Shaken to the core, Cyclops expelled the then powerless Xavier from the Institute.