I don't know if you are truly evil or merely an unwitting tool of their powers... nor does it matter! For you have chosen as your goal the Decay-- that which must be destroyed by the power of Psi! 
- — Psi src
Psi is a telepathic enemy of Supergirl.
History
Psi was Gayle Marsh, a powerful psychic born in Skokie, Illinois. Gayle was found by Daniel Pendergast, who spent years training her and indoctrinating her into believing the sorry state of the world was due to the influence of something he called the Decay, and she was the one destined to cleanse the world from it... but it'd demand a big sacrifice. Gayle was unwilling to slaughter people for the greater good even though Pendergast insisted it was inevitable.
Gayle happened upon Linda Danvers by accident, and sensing her huge powers, thought she was an agent of Decay. Gayle warned Pendergast, who freaked out and decided to push forward his plans. Gayle challenged Supergirl and her terrible telepathy and psycho-kinesis managed to knock the Girl of Steel out. Pendergast urged her to kill Supergirl, but Gayle thought she could syphon Supergirl's power and add it to hers.[1]
Psi cut a path of destruction through Chicago until Supergirl came around, witnessed the devastation, and enraged, broke free from Psi's telekinetic lock. Supergirl delivered a beatdown on Psi, who was becoming more and more uncertain of her mission. Psi teleported back to headquarters and collapsed.
When she came around, Pendergast berated her for her defeat. Gayle tried to convince him that Decay indeed had to be fought, but through other means, but Pendergast wouldn't listen. He called her useless and decided to gun her down. Feeling his anger, hatred and killing intent, Psi got frightened and blasted him with her full power. However her powers transformed Pendergast, turning him into the embodiment of what he despised: Decay.[2]
Decay set out to annihilate Chicago. Supergirl engaged him, but he was too powerful and was about to kill her when Psi interfered. She turned Pendergast back into human and ran away.[3]
During the events of Blackest Night, Psi was one of other dead Suicide Squad members resurrected as a Black Lantern [4]. She was destroyed when energy of the Green Lantern was released from a Manhunters android [5].
Powers and Abilities
Powers
Psi wielded vast psychic powers.
- Psychokinesis
- Telepathy
- Telekinesis
- Flight
- Power Absorption
- Energy Absorption
- Energy Projection
- Transformation
- Psychic Link
- Teleportation
Weaknesses
Gayle's empathic abilities are so powerful and sensitive that she can't block other people's emotions and feelings properly. Often she feels someone else's pain, hatred... like if was her own.
Notes
- Although this character was originally introduced during DC's Earth-One era of publication, their existence following the events of the 1985–86 limited series Crisis on Infinite Earths remains intact. However, some elements of the character's Pre-Crisis history may have been altered or removed for Post-Crisis New Earth continuity, and should be considered apocryphal.
Recommended Reading
Main article: Supergirl Recommended Reading
Related
- 9 Appearances of Gayle Marsh (New Earth)
- 11 Images featuring Gayle Marsh (New Earth)
- 1 Quotations by or about Gayle Marsh (New Earth)
- Character Gallery: Gayle Marsh (New Earth)
Footnotes
  Suicide Squad member |
 This character has been primarily an enemy of Superman in any of his various incarnations, or members of the Superman Family. This template will categorize articles that include it into the "Superman Villains category." |
 This character, team, or organization, is or was primarily an enemy of Supergirl. This template will categorize articles that include it into the "Supergirl Villains category." |
 Superman Family member |
 Black Lantern Corps member |