Gary Seven was a Human male whose ancestors were abducted from Earth around 4000 BC. He held the position of Class One Supervisor, known as Supervisor 194. He was grown and conditioned in some way which allowed him to have a completely healthy and flawless body; furthermore he was insensitive to the impact of the Vulcan nerve pinch.
Using advanced alien technology, including the Beta 5 computer hidden in his office in Apartment 12B at 811 East 68th Street in New York City, he continued the dead agents' mission to make sure mankind did not destroy itself with nuclear weapons.
When his transporter beam was intercepted by the USS Enterprise, it appeared that the Enterprise crew would prevent him from stopping the upcoming launch of a nuclear missile. His efforts were eventually successful. Seven used the Beta 5 exceiver circuits to cause the third stage of the American rocket to malfunction. It veered off course and the warhead exploded 104 miles above ground. This caused the nuclear powers to re-assess the risks of an orbiting nuclear platform.
He remained behind on Earth to carry out other missions with his assistants: Roberta Lincoln, a Human female from Earth of that time period to whom he accidentally described his mission, and Isis, his mysterious cat. (TOS: "Assignment: Earth")
Gary Seven was played by actor Robert Lansing. He was intended to be the lead role of an unproduced spin-off of Star Trek, with "Assignment: Earth" acting as a pilot.
Gary Seven was a central character in the first two Eugenics Wars novels, beginning with the discovery of a secret laboratory beneath the deserts of India in 1974, where Khan Noonien Singh and his fellow Augments were created. Seven, who had rescued Khan and his fellows from the laboratory before its destruction, had hoped to groom him as part of his work to safeguard Earth, but Khan's superior ambition led to the two men eventually becoming adversaries. During the Eugenics Wars of 1992-1996, Seven works to prevent the conflict between Khan and his superhuman opponents from endangering the world, and ultimately provides Khan and his followers with the SS Botany Bay after his defeat. He retires shortly after Khan's departure, leaving his supervisory position on Earth to Roberta Lincoln.
He also appeared in the novel Assignment: Eternity along with Roberta Lincoln, the short story "The Aliens Are Coming!" from Strange New Worlds III, the short story "Seven and Seven" in Strange New Worlds VI, the short story "Assignment: One" in Strange New Worlds VIII, and the short story "Rocket Man" in Strange New Worlds 9. Gary Seven was no stranger to Star Trek comics, appearing in four issues from DC Comics, "The Peacekeeper Part One", "The Peacekeeper Part Two: The Conclusion", "Split Infinities", and "Future Imperiled". He was most recently seen in the IDW Publishing series Star Trek: Assignment Earth, written and drawn by John Byrne.