Luke Hunter is the main protagonist of the series and he and his mother are the instigator of the Shackleton Cooperative's countdown to the end of the world. Luke is not supposed to be in Phoenix, as it is revealed later in the series. He is in Phoenix because Crazy Bill hacked into the computer so that Luke and his Mum would move to Phoenix so that he would meet Jordan, in order for Bill to teleport back to the past.

Peter Weir is Luke's acquaintance and he is hopelessly in love with Jordan, who does not love him back. He slowly becomes more erratic each book until he becomes uncontrollable.

Jordan Burke is Luke's and Peter's acquaintance and is Peter's love interest. She is fierce, headstrong and independent. Jordan often receives visions of the past and future and is the glue of the group.

Crazy Bill was a primary source of information for Luke, Jordan and Peter until he was taken by the Cooperative and rescued in Underground. He is seen as extremely dangerous by the citizens of Phoenix. Towards the end of fallout, it is revealed that Bill is Peter from the future. He was teleported into the past unintentionally and wants to go back to the past to see the Jordan of his life.

Cathryn Hawking along with Martin "Tank" Roper and Michael Foreman were among the first of Phoenix's citizens along with Peter and they soon abandoned him when the next wave of citizens came in.

Noah Shackleton is the C.E.O of the Shackleton Cooperative, who are planning to wipe out the human race outside Phoenix. He is super-powerful and is seen to be smart and dangerous.

Officer Bruce Calvin is the chief of the security force in Phoenix, who serve in place of police. He is feared by Luke, Jordan and Peter and they see him as a major threat.

Officer Matthew Reeve is one of few security officers in Phoenix on Luke, Peter and Jordan's side. For this reason he is killed in Contact. He is found alive in Underground.

Dr Robert Montag is the main doctor in Phoenix who starts to date Emily much to Luke's disgust. He is the one who injects the suppressors into him, Jordan and Peter in Contact and he is shot in Underground.

Emily Hunter is Luke's mother who moves to Phoenix and ships Luke with him. She is terrible at accepting bad news and wants at all costs to move on without her husband.

Jack Hunter is Luke's father. He first makes his appearance in Underground after going through a series of complications to reach Phoenix after the events of Contact.

Kara Vattel, along with Soren, her son, are the only employees left at the Vattel Complex her Kara's mother established. They initially believe Luke, Peter and Jordan to be working for Tabitha.