John Reese is one of the main protaginost in Person of Interest. John Reese was an CIA agent and Special Forces in the US Army. John had a ex girlfriend Jessica Arndt who was a nurse, he met in the army. They dated for a while. But they broke up after 9/11 and John recruited to join the C.I.A. after that. Jessica married a guy named Peter Arndt, Jessica was about to leave Peter to be with John. He was killed by Peter. After John went to her house and find out that Peter killed her, when she was going to leave him.
Peter took her out by accident, but it was murder and covered up the crime. Peter was about to frame him, until Reese took him out or buried his body in Mexico. He went reclusive and fell off the grid from the C.I.A. He was a homeless man, minding his own business. When a couple of thugs tried to harass some people, he defended their honor. NYPD took him in and cleared his misunderstanding. A guy named Harold Finch changed his life forever when he recruited him to become a member of Team Finch. He explained about the machine and use it to help people who are going to be in trouble or about to be criminals pretty soon.
He was portrayed by Jim Cavaziel.