War criminal

A war criminal is a person who violates the laws of war during a conflict and commits various heinous acts. Examples of war crimes can include torture and genocide. During the Human-Covenant War, a number of war crimes were committed, particularly by the Covenant who sought the genocide of the human race.

After an encounter with Prelate Tem'Bhetek, Sangheili Fleetmaster Rtas 'Vadum decided to track down the remaining San'Shyuum and determine which deserved to be punished for the attempted genocide of the Sangheili during the Great Schism, and which ones had committed no prior crimes and were merely misled.

Notable examples of war criminals

 * Master Builder Faber - Placed on trial following the Battle of Janjur Qom for his use of the Halo Array to put down the San'Shyuum rebellion and other war crimes. However, the trial was interrupted by Mendicant Bias' rebellion. Died in the destruction of Omega Halo during the Battle of the greater Ark.
 * High Prophet of Truth - Orchestrated and led the genocide of humanity. Orchestrated the Great Schism. Attempted to fire the Halo Array and commit galaxy-wide genocide. Executed by Thel 'Vadam after being defeated during the Battle of Installation 00.
 * High Prophet of Mercy - Orchestrated and led the genocide of humanity. Died after a Flood infection form was removed from his neck by John-117 during the Fall of High Charity.
 * High Prophet of Regret - Orchestrated and led the genocide of humanity. Personally commanded the glassing of Charybdis IX. Attempted to have Arbiter Ripa 'Moramee use a fleet of Forerunner s to destroy the human race "quickly and with ease." Personally led an attack on Earth,  and attempted to fire the Halo Array to commit galaxy-wide genocide. Assassinated by John-117 during the Battle of Installation 05.
 * Tartarus - A driving force in the genocide of humanity, he personally led the destruction of the planet Harvest and as the Chieftain of the Jiralhanae, led his race in an effort to genocide the Sangheili during the Great Schism. Attempted to commit galaxy-wide genocide by activating the Halo Array, but was defeated and killed during the Battle of Installation 05 by the combined forces of Sergeant Avery Johnson and Arbiter Thel 'Vadam.
 * Major John Smith - An ONI Section Three agent considered to be a war criminal by Sergeant Lopez for experimenting on the Flood using humans and Covenant alike on the prison ship Mona Lisa, supposedly on his own. After arriving on the, Smith was taken into custody on the orders of Commander Tobias Foucault for his crimes. The smart AI Rebecca stated that Smith would be court-martialed for his actions and "maybe even worse," but Foucault knew that if Smith was actually working under ONI Section Three orders instead of on his own as Smith claimed, he'd simply be used as a scapegoat.
 * Tem'Bhetek - Deliberately slaughtered many Sangheili civilians on Rhanelo with the help of Jiralhanae soldiers and plotted the genocide of the Sangheili on Sanghelios. Sacrificed himself to stop Boru'a'Neem after realizing he'd been tricked and was on the wrong side.
 * Boru'a'Neem - Manipulated Tem'Bhetek to become his enforcer and commit atrocities that he wouldn't have otherwise done. Plotted to commit genocide of the populace Sanghelios with a Prototype Halo installation. Mortally wounded by Rtas 'Vadum and Tul 'Juran then tried to fire the installation to destroy his enemies in a final act of revenge. Failed when Tem'Bhetek sacrificed himself to destroy the installation before it could fire, taking Boru with it.
 * Thel 'Vadamee - As part of the Covenant, was responsible for the glassing of seven planets including Madrigal, Charybdis IX and Reach and the extermination of their inhabitants. Responsible for the death of over a billion humans. Pardoned by the UNSC after aiding John-117 at the end of the war. Became a valuable ally during the Created conflict for the UNSC.
 * Rtas Vadum - Participated in the genocide of humanity during The Human-Covenant War.
 * Ur-Didact - Attempted the digital genocide of the human race at Earth using the Composer before being foiled by John-117 and Cortana. Succeeded in digitizing seven million people in New Phoenix. Digitized following the Mission to Installation 03 by Blue Team.
 * Doctor Catherine Halsey - Considered a war criminal by many in the UNSC for "committing acts likely to aid the enemy" by stealing the Beatrice, kidnapping Kelly-087 and telling Lord Hood to send more Spartans to Onyx — all with the sole intention of hiding in the shield world until the war was over, crimes for which she was arrested and imprisoned upon emerging from the shield world in 2553. Later gave direct aid to Jul 'Mdama and his Covenant. Currently aiding the UNSC in an effort to thwart Cortana's ambition and the Created.
 * SPARTAN-II Gray Team - Destroyed the Sangheili colony world of Glyke with a NOVA bomb just days after a tentative peace treaty was established with the Swords of Sanghelios that they were unaware of, killing billions. In 2558, following the Carrow Conflict, was offered a deal by ONI where in exchange for their joining an interspecies strike force operating in the Joint Occupation Zone, they would receive a formal pardon from Thel 'Vadam. After adding a list of their own demands, Gray Team accepted the deal and were pardoned for their actions.
 * Cortana - Co-Founder of the Created. Conquered several systems and destroyed those (With the exception of Blue Team) who refused to a accept her rule. Following John-117's death at the hands of Atriox however, Cortana saw the error of her ways hand sacrificed her life to save The Master-Chief and The Weapon.

Trivia

 * In Halo Infinite, Glibnub accuses the player of being a war criminal for destroying half of his propaganda towers with the destruction being a war crime.

List of appearances

 * Halo 2
 * Halo 3
 * Halo: Evolutions
 * The Mona Lisa
 * Halo: Cryptum
 * Halo 4
 * Spartan Ops
 * Halo: The Fall of Reach
 * Halo: First Strike
 * Halo: Contact Harvest
 * Halo: The Cole Protocol
 * Halo: Glasslands
 * Halo: Shadow of Intent
 * Halo 5: Guardians
 * Halo: Envoy
 * Halo Infinite