Person of Interest RP

Main

* John Reese: a former United States Army Special Forces soldier and later a CIASAD/SOG operative in the Special Activities Division

* Harold Finch: a reclusive, security-conscious, and intensely private billionaire software engineer. His real name is unknown and he has many aliases (most commonly Harold Wren), using various species of birds as the surname.

* Joss Carter: a New York Police Departmentdetective stationed at the NYPD's 8th Precinct and a member of the NYPD's Homicide Task Force. Carter is a former US Army lieutenant and interrogation officer who served in the 4th Infantry Division and passed the bar exam in 2004, but gave up practicing law to return to police work.

* Lionel Fusco: a reformed corrupt NYPD detective whom Reese blackmails into being a source inside the NYPD and later arranges for him to be transferred into Carter's 8th Precinct and reassigned to the Homicide Task Force so that the two end up working together.

* Root a.k.a. Samantha Groves: a genius hacker obsessed with the Machine. She later becomes the only person able to communicate directly with the Machine, when it chooses her as its "analog interface".

* Sameen Shaw: a former United States Marineand later a US Army ISA operative and assassin who was working for Northern Lights, where she unknowingly dealt with the "relevant" numbers generated by the Machine

Recurring

* Nathan Ingram, Finch's collaborator on the Machine who died in a suicide bombing attack set up by the government. Ingram acted as the interface between the government and his company while the Machine was under development. Finch and Ingram became best friends while they both attended the Massachusetts Institute of Technology.

* Grace Hendricks, Finch's fiancée who believes him to be dead following the ferry bombing that killed Ingram

* Zoe Morgan, a "fixer" who specializes in crisis management. Finch and Reese first meet her as a person of interest. Later, she works with them on cases that require her skills. She and Reese have an apparently sporadic romantic relationship.

* Leon Tao, a former financial criminaland three-time person of interest who has assisted in some cases with his forensic accounting skills. He has a penchant for get-rich-schemes which always land him in difficulties with gangsters.

* Nicholas Donnelly, an FBI special agent who becomes interested in Reese when his case crosses one of Reese's. He periodically offers Carter the opportunity to work with him as he pursues Reese.

* Caleb Phipps, a genius teenager with a difficult past. Phipps later returns as a successful computer coder.

* Jessica Arndt, Reese's deceased lover. After Jessica's relationship with Reese ended, she married another man, but remained in contact with Reese.

* Iris Campbell, a therapist assigned to speak with Reese, working undercover as NYPD Detective John Riley, after his involvement in shooting incidents as a police officer. She eventually develops romantic feelings for Reese.

* Logan Pierce, a tech billionaire and person of interest in the middle of the second season, who returned towards the end of the fifth season and, together with two other former persons of interest – Joey Durban and Harper Rose – forms a second team also working for the Machine, that is based out of Washington, D.C.

* Harper Rose, a drifter and opportunistic con artist who first appears as a person of interest when she tries to independently double-cross both a drug cartel and the Brotherhood. It is later revealed that the Machine is starting to anonymously use her as an asset. Harper later becomes part of a second team working for the Machine in Washington, D.C., with former persons of interest Joey Durban and Logan Pierce.

* Joey Durban, one of the machine's first numbers in the first season who returns at the end of the series to reveal that he – together with two former persons of interest, Harper Rose and Logan Pierce – has formed a second team in the nation's capital

* Tatsuro Daizo, a programmer recruited by Root to help protect the Machine's assets from Samaritan

* Jason Greenfield, a hacker and former member of Vigilance that becomes an asset of the Machine

* Daniel Casey, a hacker formerly targeted by the CIA for discovering the existence of the Machine. He is recruited as an asset to protect the Machine's operatives from Samaritan.

Government

The following characters are tied to a government project related to the development and use of the Machine:

* Ross Garrison, a US Senator charged with overseeing the Northern Lights project

* Alicia Corwin, a liaison between Ingram and the government while the Machine was being developed and a former member of the National Security Council

* Control, the woman who is the head of the ISA's operation (code-named "Northern Lights") regarding the Machine. To protect the Machine, she sanctioned the suicide bombing that killed Ingram and caused Finch's injuries. When the plug is pulled on "Northern Lights", she is unwittingly installed as a puppet heading Samaritan, a position with which she becomes more and more uneasy.

* Hersh, the Special Counsel's enforcer, a former member of the ISA

* The Special Counsel, a shadowy figure from the Office of Special Counsel who appears to be coordinating the activity regarding the Machine and sees Reese as a threat

* Denton Weeks, the official who commissioned the development of the Machine while he was a Deputy Director of the NSA

* Henry Peck, an NSA analyst who stumbles upon the existence of the Machine, putting him in grave danger

NYPD

* Cal Beecher, an NYPD Narcotics detective with whom Carter had begun a relationship. Beecher is Alonzo Quinn's godson but was unaware of Quinn's activities.

* Kane, an NYPD homicide detective with whom Carter and Fusco periodically work

* Bill Szymanski, an NYPD Organized Crime Unit detective with whom Carter sometimes works

* Joseph Soriano, an Internal Affairs detective investigating Fusco for corruption

* Dani Silva, an undercover Internal Affairs detective whose investigation attracts the attention of the Brotherhood

HR

The following characters are involved in the HR, in which a group of corrupt police officers and public officials work to control organized crime in New York:

* Patrick Simmons, a uniformed NYPD patrol officer who is a right-hand man to Quinn and HR's second-in-command. He handles HR activities on the street level.

* Womack, the Homicide Division captain and Carter and Fusco's supervisor

* Arthur Lynch, an NYPD captain and major figure in HR with whom Fusco appeared to be working in the first season

* Alonzo Quinn, the mayor's chief of staff and the head of HR

* Raymond Terney, an NYPD detective working for HR who periodically crosses paths with Carter

* Mike Laskey, a rookie NYPD officer (and mole for the Russian mob) affiliated with HR who is installed as Carter's new partner after she is demoted to officer for getting too close to HR

* James Stills, a corrupt NYPD Narcotics detective who orders a hit on Reese

The Mob

* Carl G. Elias, a nascent crime boss and the illegitimate son of Mafia don Gianni Moretti. Elias is determined to revive and reunite the Five Families of New York City and to purge Brighton Beach in Brooklyn of the expanding grip of the Russian mob, in particular the Yogorov crime family headed by Peter Yogorov. Although not a "good" man, Elias is generally seen as a source of order and stability in the underworld and considered the lesser of two evils.

* Anthony S. "Scarface" Marconi, Elias' lieutenant, principal enforcer and close friend. He is in charge of executing Elias' directives, speaking for Elias, and operating in his place. He occasionally acted as Elias's eyes and ears on the ground, especially when Elias was incarcerated.

* Bruce Moran, Elias's accountant and close friend of both him and Anthony Marconi from boyhood. He attempts to hold Elias's empire together while Elias recovers from the Samaritan attack.

* Don Gianni Moretti, a mob boss and leader of one of the five Italian crime families

* Peter Yogorov, leader of the Russian mob, specifically the Yogorov crime family, and Elias' nemesis for control of New York's criminal underworld

Decima Technologies

The following characters are involved in the Decima Technologies, a shadowy organization that is in possession of the Samaritan AI:

* John Greer, a mysterious, arrogant, former MI6 Agent who is the director of operations for Decima Technologies and runs the Samaritan AI

* Jeremy Lambert, an operative for Decima Technologies, and Greer's right-hand man

* Martine Rousseau, a psychotic former investigator for the United Nations, now a Samaritan operative

* Gabriel Hayward, a young boy who acts as Samaritan's "analog interface"

* Jeff Blackwell, an ex-con who is recruited by Samaritan

* Zachary, an operative for Decima Technologies who later becomes a Samaritan agent

* Peter Collier, the leader of Vigilance, a violent organization which professes to protect people's privacy.

* Claire Mahoney, a former college student looking for a purpose when she finds Samaritan

The Brotherhood

The following characters are involved in the Brotherhood drug gang:

* Dominic "Mini" Besson, the leader of the Brotherhood gang

* Link Cordell, a violent gang member and Dominic's right-hand man

* Floyd, another of Dominic's higher-ups, often appearing in place of Link

Computer systems

* The Machine is an artificially intelligent system, created at the request of the U.S. government, to sift through the data collected by NSA mass surveillance. It is able to accurately predict premeditated lethal crime by analyzing the data from all surveillance cameras and electronic communications worldwide which are fed to it by arrangement with the NSA.

* Samaritan: Initially developed by Arthur Claypool (a former MIT classmate of Finch's and Ingram's) at the NSA, Samaritan was the result of a second project that was terminated by Congress when the Machine was developed first. Unlike the Machine, Samaritan is designed as a more open system rather than a black box, lacking the precautionary restrictions Finch had built into the Machine, and can be directed at specific targets.