"You know that I just returned from a mission to Italy. You also know that I'm retired military. Fought in every war from 'Nam to the Gulf. What you don't know is that I'm retired CIA. Expert, trained hitman."
- Stone explains his activities during a mission to assassinate Dimitri

Stone's commendation

Stone's dossier

Stone's Medal of Courage - a Purple Heart

Stone's report of beef that was sent to Italy and not Belarus

Stone's record from the Vietnam War
Stone is the Intelligence operations commander of IPCA.
Background
Stone is a hard edged combat veteran who has seen action in almost every American conflict since Vietnam. He lead units in Libya, Grenada, Panama, Iraq, Somalia, Bosnia and Afghanistan. He was also a CIA assassin.
Description
Gary Stoneman, also known as Stone, is one of the Agency's operations commanders tasked with gathering intelligence or executing Discreet Personnel Elimination (DPE) orders. He has worked alone on several assignments but is capable of leading field units into hostile territory.
Much of Stone's previously classified history includes his tenure as an agent of the CIA. While a member of the U.S. Marines, he displayed skills with a sniper rifle and became a CIA recruit for high-profile assassinations. In the seventies Stone was responsible for the murder of fifteen Viet Cong among other targets.
His role took him to the U.S. Special Forces and to Libya and later Grenada in the eighties, where he befriended Gabriel Logan after a rescue from enemy forces. Stone also encountered future associate Imani Gray in Panama, and was in the Middle East during the Gulf War, later gaining the trust of Kuwaiti-born Alima Haddad.
Stone's assassinations in the nineties occured in Somalia and Bosnia before Gabriel Logan recruited him into the reformed Agency. Stone oversaw the Agency investigations of the Omega Strain in Italy, and assassinated Mafia boss Dimitri Alexpoulous to prevent him from purchasing the virus. He would later track Mikhas Ivankov and the Chechen Democratic Partizans in Belarus, only to have Alima captured by the terrorists.
Commander-in-Chief Logan used Stone to steal weapons contracts from Fatha Al-Hassan in Yemen, and Stone could resume his search for Alima. In Ukraine, he was successful in liberating her from a CPD cell and allowing her to receive medical attention. The Agency prevented the terrorist threat and Logan ordered Stone to carry out one more related assassination. Stone traveled to the town of Narbonne and eliminated both Mara Aramov and her lover, Dr. Elsa Weissinger.
Plot
Syphon Filter The Omega Strain
He leads the agents of IPCA in missions in Belarus. He is sent to Italy to assassinate Dimitri Alexopoulos; he is caught and interrogated by Pulikovsky in Belarus; he pilots a helicopter in Yemen to rescue Zohar and the IPCA operatives; and he rescues Alima Haddad in Ukraine. In one of the last cutscenes of the game it is shown that he was sent to kill Mara Aramov.
Syphon Filter Dark Mirror
Stone makes a few appearances in the game: the mission he is sent to eliminate Aramov Mara and Elsa Weissenger in the Narbonne, France mission. He is also a playable character when taking out terrorist insurgents in Yemen. He is also mentioned by Singularity in the last mission.
Syphon Filter Logan's Shadow

Imani's journal complaining about Stone

Stone's report of a Belarus party selling beef to the Cosa Nostra

Gabe's journal on first meeting Stone

Stone's instructions for the mill mission

Stone's mission on the Belaya Vezha

Stone's compliment of the IPCA recruits and complaint that he lost Alima

Stone's report of threatening Zohar and the latter's handing over of Yushchenko's sample
Stone is absent from the main game, but Gabe makes mention of him in hidden evidence, particularly where he always told Logan of his horror stories about friendly fire. Most of them ended with the phrase, 'There ain't nothin' friendly 'bout friendly fire!"
List of known victims
- Phuoc Huu Nghiem (VC leader Phu Loc)
- Huynh Kha'n Pho' (governor VC admin)
- Quang Anh Dung (official of state)
- Huy Lanh Trung (Commander Sun Group)
- Bao Giang Chu (Commander NLF)
- Dac Luo Lo (Agent NLF)
- Huynh Lai Chu
- La'nh Kien Lai
- Nguyen Hu'ng
- Huy Lo Bui
- Nhat Bao Lai
- Lanh Mai Niem
- Truc Dung Duo
- Ma Hien Huy
- Cuong Ang Dun
- Panamanian dictator (mentioned in Omega Strain manual)
- Dimitri Alexopoulos (killed with headshot)
- Mikhail Pulikovsky (if Cobra does not kill him)
- Mara Aramov
- Elsa Weissenger
- Fatha al-Hassan (non-canon victim; Zohar kills him in Omega Strain and Stone 'kills' him in Dark Mirror)
Appearances
Syphon Filter: The Omega Strain
- Prologue
- Carthage, Michigan: Warehouse District (mentioned)
- Carthage, Michigan: Carthage Mall (mentioned)
- Pescara, Italy: St Cetteo's Square
- Mazyr, Belarus: Krivorozhstal Mill (cutscene and voice)
- Mazyr, Belarus: Belaya Vezha
- Sana'a, Yemen: Taherir Palace
- North Atlantic: Lorelei Salvage Rig (mentioned)
- Kiev, Ukraine: Chechen Terrorist Base
- Epilogue
Syphon Filter: Dark Mirror
Syphon Filter: Logan's Shadow
Trivia
- Stone may be one of the few Agency members still alive following the end of Logan's Shadow. The other survivors are Cobra, Gina Hunter and Lian Xing.
- He will teach his 'neck snap' to IPCA agents if they complete the 3 Carthage missions within solo deadlines.
- Unlike Gabe and Lian, Stone seems to have very little health when playable.
- Paul Eiding, who voiced him, is also the voice actor of Colonel Campbell from the Metal Gear Solid series.
- Teresa believes him to be 'too old' or otherwise incapable of carrying out operations in The Omega Strain.
Information about Gabe and Stone's journey to Moscow