Breaking the Fourth Wall/Fan Works

In the Total Drama Island fanfic Total Sibling Rivalry, after the author's self-insertion, Chris wonders about buying a new fourth wall.
One Regular Show fanfic features Mordecai and Rigby jumping out of the show using a "Cartoon Leaper 3000". They even proclaim that "This show is getting boring anyway!"
In the Axis Powers Hetalia fanfic It's a Small World After All, the characters warn each other not to break the Fourth Wall often so that the fangirls reading the story (including the author) can't get in. However, a lot of the characters (usually Japan) end up breaking the Fourth Wall in the middle of the story (via looking up at the ceiling and complaining to the author) and cause a war in the author's note over 'keeping the Fourth Wall up'. Fangirls obliterate the Fourth Wall and take over the fanfic for a chapter, after which everyone agrees on inserting a Fourth Wall with a door.
In the Castaways of the Flying Dutchman fanfic A Spoof from the Castaways of the Flying Dutchman, the author spoofs the story in an entertaining way using Self Insert and brutally honest--sometimes exaggerated or downright made up--ways of depicting the events occurring, all the while beating the shit out of the fourth wall as they move the story along.

Ben: Oh look, a note! (Reads note) Oh fun, I get to sneak out tomorrow. Maybe something interesting will happen in this story.
Me: You mean like a faster update? Like that will ever happen.

A common source of humour in the Tamers Forever Series; often it's the author doing the forth wall breaking with random comments.
In the Star Wars/Veggie Tales crossover Larry Boy and the Little Man of Purpleness, the trailer ends with these lines:

Han: Excuse me as I break character here: To the author: About this dialogue, are you on some form of illegal substance?
Wedge: And could we please have some?

In context, however, Han's only breaking the fourth wall in a play they're rehearsing.

In chapter 6 of the My Little Pony: Friendship Is Magic fanfic The Monster Mash, this is played for a mixture of drama and dark comedy with side orders of Go Mad from the Revelation and Humans Are Cthulhu.
- Pinkie Pie breaking the fourth wall to acknowledge or even directly address the readers and/or the author is something of a Running Gag in FiM fanfiction in general. Sometimes other characters get in on the act, more often it's waved off as her just being Pinkie.
In the Avatar: The Last Airbender parody Bring Me All Your Elderly, the Animated!Characters not only are aware that they are animated (and discuss it very casually), they also leave the Animated!Universe to enter the Movie!Universe, generally blame all unexplained events either on the fanfic author or M. Night Shyamalan, read their own fanfic and comments straight off the internet, and basically suffer severe existential crises as a result. The fourth wall itself actually makes a brief appearance at one point in the story, along with a sign that says "fragile."

Mai: But for future reference, guys - try to be careful about breaking the fourth wall around Zuko, okay? He doesn't know, and it tends to freak him out a little.
Zuko: Fourth wall? What wall? Someone broke a wall?
Mai: Nothing, Zuko. Just don't worry about it.

In the Naruto fanfiction series Quiet by MaliceArchangela, partway through the first story Quiet on the Golf Course, Itachi Uchiha starts routinely breaking the fourth wall, speaking with the author to the point that the breaking happens every chapter, and allows reviewers to communicate with Uchiha.
One Star Ocean fanfic titled Aquios High has one memorable scene where Cliff, under the influence of some sort of drug (I can't remember, think it might have been alcohol), explains to everyone about the authoress responsible for everything. Since the author decided to turn the fic into an actual book, it might not be online anymore.
The third Magical Girl Lyrical Nanoha "Toward the World's End" fanfic Mission Fail has the protagonist Arthur talking to the reader, including saying things like "But you already know that".
Happens often in the Calvin at Camp series, especially when the Hitchhiking Ghosts are involved.
Despite it being in a First Person Perspective, The Spice Girls Fic Astral Journey: It's Complicated often have Emma talking to the readers, in "Italic".
After seeing what Emma was subject to in Final Stand of Death, Victoria and Geri tells Mel. Mel tells them she been paying attention to the story and brushes off.
The Importance of Being Ranma, a 1990s-vintage Ranma ½ fic by "SMoonUsagi" and "RyogaLost", has a classic example that actually developed out of the plot. After it's revealed over the Tendo dinner table that Ranma and Ryoga are half-brothers, there is this moment:

"You know," Kasumi said to no one in particular as she started clearing the table, "I always did think Ranma and Ryoga looked quite a lot alike."
"Yeah," Nabiki concurred, "but I always thought that was just the art style."
"Hush, Nabiki," chided Kasumi, "Takahashi-sama might hear you."
"Oh, right, like she actually reads this stuff..."
"Would you two stop tearin' down the fourth wall and get back to the story?!" Ranma shouted.

My Apartment Manager is not an Isekai Character: Dimensional displacee Ferris Bueller is aware he's in a fanfic and acknowledges the readers in some way whenever he appears.