Psycho Mantis (voiced by Doug Stone and Kazuyuki Sogabe) is a psychic expert for the FOXHOUND unit. Prior to joining FOXHOUND, he worked with the KGB and the FBI. His special abilities include the psychic powers of psychokinesis and telepathy. He also claims to be able to read the future, but this is implied to be a use of telepathy to find out what his opponents will do next as opposed to true clairvoyance. In Metal Gear Solid Mantis encounters Snake twice, the first time he takes control of Meryl's mind, the second encounter he and Snake do battle, with Mantis being defeated.[45]

When Solid Snake faces Mantis, Mantis demonstrates his psychic powers by breaking the fourth wall. In the pre-battle cut-scene, he activates the controller's rumble feature, then reads the player's memory card and comments on how often you saved the game and your preference on certain other games. In the original PlayStation game, he reads off the titles of Konami's other games (Castlevania: Symphony of the Night, Suikoden, among others), while in the remake Twin Snakes, he reads Nintendo's games (Super Smash Bros. Melee, Super Mario Sunshine, The Legend of Zelda: The Wind Waker, and Eternal Darkness: Sanity's Requiem, among others).[46] Then, at the beginning of the actual battle, Mantis causes the screen to go completely black except for the words "HIDEO" in green all capital text in the top right corner of the screen, much like TV or VCR on-screen-displays, in an attempt to throw the player off; as well as "reading" the player's input on the controller and hitting the player, counterable by using the second player controller port (Mantis then complains about how he cannot read your mind).[47] Psycho Mantis was named the "Second greatest boss" by Electronic Gaming Monthly in their 200th issue.[48]