Deadpool (Marvel) is aware that he is in a comic book and able to express his thoughts via captions.
Be aware of the 4th wall.
The ability to be aware that one's Universe is fictional, and potentially use this to act in otherwise impossible ways within their fictional universe.
Fourth Wall Breaking
Users have the capacity to be aware that their Universe is false. Through this, they may be able to carry out acts that, within the Universe, would otherwise be impossible. Depending on the extent of the user's power, one could potentially gain the powers of Reality Warping and/or Omniscience within the context of their own false Universe.
People that use this ability may appear to be abnormal to every one else, and it may be difficult at times to hide the fact that you have this ability. Coupled with their potential influx of wild information, users have an increased likelihood of being driven completely insane.
Pinkamena Diane "Pinkie" Pie (My Little Pony: Friendship is Magic)
Edd (Edd Egg)
Many characters (The Grim Adventures of Billy & Mandy)
The Powerpuff Girls (TPPG's)
Discord (My Little Pony: Friendship is Magic)
Homer Simpson (The Simpsons)
Bart Simpson (The Simpsons)
Kodos and Kang (The Simpsons)
Najimi Ajimu (Medaka Box)
Most Characters (Randomverse)
Many characters (Kid Icarus: Uprising)
Weeping Angels (Doctor Who)
Mosley "Mo" Mobile (Mobile Mysteries)
Sonic The Hedgehog (Adventures of Sonic The Hedgehog)
Zack Morris (Saved by the Bell)
Batman (Batman: The Brave and the Bold)
Slade (Teen Titans: Calling All Titans game)
Peter Parker/Spider-Man (Ultimate Spider-Man TV series)
Junko Enoshima/Monokuma (Dangan Ronpa)
Several Characters (Hyperdimension Neptunia)
Several Characters (Bastard!!)
Player Character (Dragonfable)
Fry, Bender, Leela, and Professor Farnsworth (Futurama: The Game)
All Characters (Dr. Slump)
Bat-Mite (DC Comics)
Ice King (Adventure Time)
Don Knotts (Johnny Bravo)
Weird Al Yankovic (Johnny Bravo)
Blue Falcon (Johnny Bravo)
Ninja Turtles (Teenage Mutant Ninja Turtles)
Kirihime Nastuno (Dog & Scissors)
Pit (Kid Icarus Uprising)
Palutena (Kid Icarus Uprising)
Viridi (Kid Icarus Uprisin)
Hades (Kid Icarus Uprising)
Gintoki Sakata (Gintama)
Shinpachi Shimura (Gintama)
Kuzco (The Emperor's New Groove)
Ferris Bueller (Ferris Bueller's Day Off)
Scott Pilgrim (Scott Pilgrim comics)
Deadpool (Marvel) shows awareness that he is in an illustrated story.
Uatu the Watcher (Marvel)
Pinkie Pie (My Little Pony: Frendship is Magic) can view and shatter the fourth wall.
Ajimu (Medaka Box) is aware that she is in a manga and will be animated.
Neo (The Matrix) is aware that The Matrix is a false existence, and as such can manipulate its reality, stopping bullets in their paths.
The title character of the film Rango is aware of the fact that he's a fictional character in the film.
Many Kid Icarus: Uprising characters like Pit and Viridi, often break 4th wall by making video games references or mentioning that they're in a video game themselves
Sonic talking to the audience in the show's segment "Sonic Sez"
Lyssa Drak (DC)
Kirihime Nastuno - "The protagonist has enter the story." (Dog & Scissors)
Kuzco (The Emperor's New Groove)
Scott Pilgrim (Scott Pilgrim comics) frequently shows an awareness that he's in a fictional universe, telling many other characters to "read the book" when they ask questions regarding the events of previous chapters or volumes.