Wade Wilson/Deadpool's (Marvel Comics) awareness that he is in a comic...
Uatu the Watcher (Marvel Comics)
Pinkie Pie (My Little Pony: Frendship is Magic) can view and shatter the fourth wall.
Discord (My Little Pony: Friendship is Magic), like Pinkie Pie, is capable of breaking the 4th wall.
The Storm King (My Little Pony The Movie) is happy to demonstrate this while being inside a comic book.
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".
Kirihime Nastuno (Dog & Scissors) - "The protagonist has enter the story."
Kuzco (The Emperor's New Groove)
Scott Pilgrim (Scott Pilgrim comics) frequently shows an awareness that he's in a fictional universe, telling other characters to "read the book" when they ask questions regarding the events.
The Squid Sisters (Splatoon), Callie (left) and Marie (right), are aware that they are in a video game and occasionally reference that fact.
The Twelfth Doctor (Doctor Who) tells the viewers to Google the Bootstrap Paradox.
Neptune (Hyperdimension Neptunia) breaks the fourth wall.
Uncle Grandpa (Uncle Grandpa) is shown to be aware of the fact that he is in a cartoon, and would sometimes acknowledge the fictional world around him and the viewer.
Sardonyx (Steven Universe) is implied to have a limited awareness of the fictional nature of her show, making references to it as she gets to know Smoky Quartz, such as refering to one of the voice actors and to Cartoon Network itself.
Tamatoa (Moana) is slightly aware that he is in a Disney film.
Control Freak (Teen Titans) is completely aware that he is in an animated series and has even found a way to cancel the original Teen Titans and reboot it which resulted in the creation of Teen Titans Go!
Mine's (Akame Ga Kill!) Wheel of pain (With Gangan Joker's Mangas)
Card Collector (Valkyrie Crusade) is aware she is in a game, and even thinks that her power should be used on it.
Lincoln Loud (The Loud House) frequently speaks to the viewer as a means of coping with his large family, and eventually passed the secret on to his friend, Ronnie Anne Santiago.
On April Fools' Day, Luan Loud's (The Loud House) comedy becomes strong enough to break the Fourth Wall.
The Squid Baron (center) (Shantae series) is aware he lives in a videogame, which often rubs off on Shantae.
Frank Underwood (House of Cards) frequently blurts his ambitions to the audience, and no one's the wiser.
Elliot Alderson (Mr. Robot) often likens the audience to an imaginary friend.
While not fully conscious of their fictional nature, Rosencrantz and Guildenstern (Rosencrantz and Guildenstern are Dead) do possess a limited awareness of the absurd nature of the events that surround them.
From his actions and words, it is made clear that the Player King (Rosencrantz and Guildenstern are Dead) is aware that he, Rosencrantz and Guildenstern are fictional characters acting out a story on repeat.
Due to her mental instability, Senua (Hellblade: Senua's Sacrifice) can see and speak to the player.
Sans (UNDERTALE) frequently acknowledges gameplay devices, such as LV and EXP.
Rick Sanchez (Rick and Morty) is fully aware that he is a fictional character in a cartoon and makes a habit of mentioning it whenever possible or during the final episode of the season.
Johnny Test (Johnny Test) "Now that's how you end a story."
Dukey (Johnny Test) "It's like this everyday in this house."
Susan Test (Johnny Test) "Thought it was a sweet ending to this story."
Bling-Bling Boy (Johnny Test) "It took me 4 seasons to kiss Susan."
Santino Marella (WWE SVR 2010) "You're what some loser would create in a video game!"
He then looks at the viewers and gives them a wink.
Chris Jericho (WWE SVR 2009) talking to the viewers.
CM Punk (WWE SVR 2009) talking to the fans while holding the camera.
John Cena (WWE SVR 2009) shoving the camera.
Triple H (WWE SVR 2009) "I've been down the Road to Wrestlemania countless times, but this time, you've got control. It's time to play the game!"
Edge (WWE SVR 2011) "Dude, we totally fooled the player into thinking we weren't going to reunite!"
Edge: "You see that weirdo staring at us through the TV?" Both Edge and Christian look at them.
Harley Diaz (Stuck in the Middle)
Clarissa Darling (Clarissa Explains It All)
SomeCleanTrash (TF2 Freak) is able to not only be aware of the fourth wall but is able to use the captions on the screen as weapons