Psycho Mantis (Japanese: サイコ・マンティス), born Tretij Rebenok, is a fictional boss character in Konami's Metal Gear video game series.

Psycho Mantis first appears in Metal Gear Solid, where he helps main antagonist Liquid Snake in his attempt to capture Shadow Moses Island.

Protagonist Solid Snake receives romantic advances from his ally Meryl Silverburgh, only to discover that she is being psychically controlled by Psycho Mantis.

[6] According to Mantis, he joined with Liquid Snake, the game's main antagonist in order to "kill as many people as he could" as he had grown disgusted with the human race.

Mantis tries and fails to repeat the same display of his powers from Metal Gear Solid due to the PlayStation 3's lack of memory card.

[10] A younger version of Psycho Mantis appears in Metal Gear Solid V: The Phantom Pain, where he is a child under the name Tretij Rebenok.

He is manipulated by the game's main antagonist, Skull Face, who uses Rebenok to control a Metal Gear robot with the goal of killing all English-speaking people in the world.

[19] The comic adaptation of the game had Mantis appear on a cliffhanger, threatening to use his powers to make Meryl shoot herself, before seemingly being defeated by Snake's ally Master Miller.

[21] A Brief History of Video Games noted how breaking the fourth wall was both varied and unique, making the battle "a bravura performance rather than a mere novelty"[7] Hideo Kojima later stated that Psycho Mantis was his favorite character in the series.

[12] Filmmaker and director Guillermo del Toro additionally praised the Psycho Mantis scene for being able to transcend the video game medium.

[22] Andy Kelly of TheGamer praised the character as part of what made Metal Gear Solid so iconic, describing how the Mantis battle utilized the video game medium in unique and inventive ways.

[23] Brendan Main of The Escapist posited that Mantis's ability to unnerve the player with their save data was an experience that was not replicable outside of Metal Gear Solid itself.

[29] The book Once Upon a Pixel: Storytelling and Worldbuilding in Video Games additionally stated that this ability made Mantis more terrifying as an opponent.

This created conflicting feelings of identification and alienation, with Mantis's actions pushing the player out of the normal game flow they were experiencing as Snake.