John Grayson is the father of Dick Grayson, and the husband of Mary Grayson. He is the leader of the leader of the Flying Graysons, a team that preforms aerobatic tricks without the safety of a net. He can perform triple flips, while his son can perform four flips in a row. John and Mary Grayson were both killed by the mob boss known as Anthony Zucco. An event which led to young Dick Grayson to be adopted by Bruce Wayne as his young ward.
He and his wife appeared in Batman: Blackest Night, as Black Lanterns. Dick nearly let them kill him until he remembered that they weren't really his parents.