Clayton Riddell is a struggling artist who is estranged from his wife, Sharon, and his young son, Johnny, in the Stephen King novel Cell. He is originally from Kashwakamak, Maine. After The Pulse, Clayton wanders the apocalyptic world with Alice Maxwell and Tom McCourt.
In the film adaptation he is played by actor John Cusack.
In the novel, he is buying an ice cream cone after selling his first comic, when The Pulse hits. He takes refuge in a hotel with Tom McCourt and Alice Maxwell, as the city starts to blow up. They escape the town, which is now dark with ash all over the deserted, apocalyptic town, just in time. The city burns down, killing anyone left in the city. Clay and the group reach Gaiten, and find twelve year old Jordan, the only student in the boarding school not affected or killed by The Pulse and his elderly principal, Charles Ardai, who are taking refuge in the boys dorm. Charles Ardai kills himself, but Jordan and the gang escape the school just as it burns down. Clay was one of the rescuers after Alice was hit by a car, and tried to save her but she died in his arms. Clay eventually leaves the group after successfully killing The Raggedy Man and finds his son Johnny, who received a bad dosage of The Pulse, and has lost most of his memory and doesn't know how to function. He drives Johnny home and tucks him in bed. Clay dials 911 and puts the phone to Johnny's ear, hoping to send his son back to normal. The story does not confirm whether this worked or not, so whatever happened to Johnny and Clay is unknown.
Clay is seen as a normal single father, who still cares about his ex wife, and cares deeply about his son. He would do anything to save him, and often almost has panic attacks about his son's welfare.