Psycho Mantis

Psycho Mantis is a character from the Metal Gear games.

Psycho Mantis as a psychic member of FOXHOUND, who participated in the armed takeover of Shadow Moses Island in 2005. He wore a special gas mask to help prevent people's thoughts from "forcing their way into his mind."

In 1984, Mantis primarily found himself attracted to those who harbored negative feelings, thus accompanying the "Man on Fire" in his pursuit of vengeance. He would later work as a child soldier for XOF under the code name Tretij Rebenok (Russian for "Third Child"), until finally defecting from the organization after allying himself with a young Liquid Snake.

Appearance
As "Tretij Rebenok", he possessed messy red hair, and wore a gas mask and a black straitjacket. By the time of the Shadow Moses Incident, Mantis possessed an emaciated body and a hairless skull while sporting a black bodysuit and a trenchcoat. He had a misshapen nose, with surgical scars and stitching adorning his cranium and lower face, causing Mantis to despise his own appearance to such an extent that seeing any depictions of his disfigured face would force him to break his concentration though it's unclear why he would have busts of his own face.

Personality
Mantis rarely spoke and his powers seemed much more amplified. He was aimless in his goals and often sought the company of those who possessed "evil" thoughts such as hatred or a lust for revenge. This would result in him appearing to possess characteristics based on his attachment towards a respective host, e.g. the flames derived from Volgin, Venom's shrapnel "horn", Skull Face's domino mask, Eli's red beret on his shoulder during his days as a boy, and very briefly Shabani's necklace. His psychokinesis and telekinesis were such that he was able to move large objects such as debris and military vehicles, as well as control a Metal Gear with no visible signs of straining himself. He was shown to be capable of manifesting himself as a phantom that could teleport or vanish in an instant and could conjure ethereal visions derived from a person's psyche. His psychokinesis was also strong enough to envelop a barrier powerful enough to deter attacks from various weaponry, including small-grade portable rocket/missile launchers, against himself and objects as large as a parked chopper. It is heavily implied that his being drawn to people who possessed "evil" thoughts, or at least those from Venom Snake/Big Boss, was due to having a degree of empathy for their desires for revenge due to his being experimented on for his powers to such an extent that he otherwise lacked any will or even emotions beyond a desire for revenge of his own.

When influenced by the negative feelings of others, he was capable of channeling himself as a conduit, enacting the lusts of his respective host through his abilities - this is what allowed Skull Face and later Eli to control Metal Gear Sahelanthropus. Though Volgin and Skull Face would interchange between influencing his mind, Mantis would go on to develop a bond with the young Liquid Snake, thus supplanting Volgin and Skull Face's control over him. Though Liquid's resentment over his heritage acted as the catalyst for Mantis' attraction towards him, it was their shared young age that allowed Mantis to favor him over many others that influenced him before. It is heavily implied that this bond served as the basis of his joining FOXHOUND with Liquid as the leader.

As he matured, he began to speak more and gained more control over his catastrophic powers. Mantis's work with the minds of serial killers for the FBI caused him to develop insanity. He also held nihilistic views, feeling disgust towards humanity's ultimate lust to simply reproduce, and the "selfish" passing on of one's genes. He even implied that this desire was ultimately the reason why war existed. His contempt was such that, during his death, he freely admitted that he didn't actually care for Liquid Snake's goals, and had only collaborated with the Sons of Big Boss in order to kill as many people as he could. It is heavily implied that his nihilism and misanthropy stemmed from his terrible childhood, including his discovery of his father's infanticidal hatred of him by accident and his later being used as a living weapon and experiment by the Soviets. Despite his insanity, Mantis also displayed some skill in strategizing, having originated the idea of using Decoy Octopus to impersonate the (then-recently) deceased DARPA Chief, which succeeded in tricking Solid Snake into activating Metal Gear REX.

Abilities
Psycho Mantis was a powerful practitioner of psychokinesis and telepathy, with Nastasha Romanenko considering him to be one of the most powerful psychics in the world. He was capable of moving objects with the power of thought, spinning them around himself to create a makeshift barrier, or throwing them towards an opponent. He was also capable of generating a ball of psychic energy, as evidenced during his battle with Solid Snake. Through telepathy, Mantis could read people's minds and learn about their pasts. This power could even be extended to mind control, which he used to sway members of the Next-Generation Special Forces into joining FOXHOUND's revolt, and to force Meryl to attack Snake. However, his telepathic abilities could be rendered ineffective if his subject was either strong willed or possessed surgical implants in their brain, as evidenced by his failure to defeat Solid Snake in battle, and to read Donald Anderson and Kenneth Baker's minds, respectively. Because of his constantly wearing a gas mask to ensure he focused on his psychic powers, he frequently had a rasping breath accompanying him.

Trivia

 * Psycho Mantis was chosen as the #3 best boss fight ever by GameSpot.
 * He also ranked eighth in IGN's recent "Top 100 Videogame Villains" poll, beating out fellow FOXHOUND members Sniper Wolf, Liquid Snake, and Revolver Ocelot; even beating Big Boss.
 * The boss battle with Psycho Mantis in Metal Gear Solid is widely remembered for him "displaying" his mental powers through breaking the fourth wall. This includes making the controller move by activating the rumble feature, and making players think the TV channel has changed by turning the screen to black, with the green caption "HIDEO" displayed in the top-right corner. He also "reads" the player's memory card, commenting on the number of saves that have been made in the game so far, and the presence of other saved games, first noting their genre, then mentioning specific examples (e.g. "You like Castlevania, don't you?").
 * In the original game, Mantis mentions Azure Dreams, Suikoden, Castlevania: Symphony of the Night, and Vandal Hearts (plus Policenauts and Tokimeki Memorial in the Japanese version), while in the 2004 remake, he references Super Smash Bros. Melee, Super Mario Sunshine, The Legend of Zelda: The Wind Waker and Eternal Darkness: Sanity's Requiem. He was originally planned to reference games made by other developers as well, but they weren't included because Kojima couldn't make any deals with them.
 * Mantis' powers were inspired by another fictional psychic character from the 1978 film The Fury, with Hideo Kojima telling his motion designer to go see it.