In the novel, Johnny Smith was initially a normal English teacher in New England, the only slight mar in his past being a fall on an ice rink when he was six years old in 1953 which he barely even remembered as an adult. After a date with his current girlfriend Sarah to a county fair, he was caught in a car crash when sent him into a coma for four and a half years until May 17, 1975. When he regained consciousness, Johnny and his doctors swiftly discovered that, apparently due to seemingly minor brain damage sustained while he was in his coma- affecting his ability to remember numbers and addresses-, a long-dormant part of his brain relating to touch had been reactivated, granting him the ability to touch people and objects and learn something about their pasts or futures.
Despite his use of these abilities only ever being benevolent, such as to warn a woman that her kitchen was on fire, Johnny eventually denied their existence, the only exception being when he was contacted by a sheriff seeking assistance in tracking a serial killer. Having found the killer, Johnny went into semi-retirement once again, taking a job as a private tutor when he found himself unable to return to his old teaching job on the grounds that he was 'too controversial' to be an educator. During a political rally, however, he shook hands with candidate Greg Stillson and foresaw an apocalyptic future that would take place if Stillson won the election.
Although reluctant to resort to murder, Johnny's hand was forced when he discovered that he had developed a tumour as a result of his accident, leaving him with only a limited time to live. With no hope of gathering evidence to expose Stillson's threat in the time left to him, Johnny instead purchased a sniper rifle and attempted to shoot him at a press conference. Although Stillson survived and Johnny was killed by his security force, Stillson's reaction to the attack- particularly when he grabbed a child and attempted to use the boy as a shield- ruined his election chances for good, Johnny managing to reassure himself of this by grabbing Stillson's leg briefly before he died.
In the television series Johnny was introduced in the pilot episode, "Wheel of Fortune (Part 1)". Born John Robert Smith in 1967, Johnny taught Biology at Cleaves Mills High School until a horrific car crash on 6 June 1995 put him into a six-year coma from which he awoke on 1 September 2001. Since that time, he has experienced psychic visions, triggered by physical contact, of the future and the past; he has repeatedly used these visions to aid Penobscot County Sheriff Walter T. Bannerman, the man who had married Johnny's own fiance, Sarah Anne Bracknell, and subsequently helped her raise Johnny's son J.J. (Who Shares his abitlites, which is not revealed until the series finale), while Johnny was comatose. Unlike his novel counterpart, Johnny is very relaxed about the use of his abilities, using them on several occasions to help his friends investigate the mysteries and dangers surrounding them.