Fourth wall

The fourth wall is the imaginary "wall" at the front of the stage in a traditional three-walled box set in a proscenium theatre, through which the audience sees the action in the world of the play. The concept is usually attributed to the philosopher, critic and dramatist Denis Diderot. The term itself was used by Molière. The fourth wall illusion is often associated with naturalist theatre of the mid 19th-century, and especially with the innovations of the French director André Antoine.

The restrictions of the fourth wall were challenged in 20th-century theatre. Speaking directly to, otherwise acknowledging or doing something to the audience through this imaginary wall – or, in film, television, and video games, through a camera – is known as "breaking the fourth wall". As it is a penetration of a boundary normally set up or assumed by works of fiction, this is considered a metafictional technique. In literature and video games, it occurs when a character acknowledges the reader or player.

Breaking the fourth wall should not be confused with the aside or the soliloquy, dramatic devices often used by playwrights where characters on stage are delivering inner monologues, giving the audience insight into their thoughts.

There have been a few moments in the Scooby-Doo franchise when the fourth wall has been broken.

Scooby-Doo, Where Are You!

 * A Clue for Scooby Doo - At the end of the episode, Scooby-Doo winks at the audience.
 * Hassle in the Castle - After Scooby steals his sandwich, Shaggy Rogers looks at the audience and tell them "With him around, I can't even get a bite in etch wise".

The 13 Ghosts of Scooby-Doo

 * Scoobra Kadoobra - The episode is interrupted.

A Pup Named Scooby-Doo

 * In every episode, a member of the gang narrates the story.

Be Cool, Scooby-Doo!

 * Poodle Justice - Daniel Valentino comments on seeing Velma Dinkley's mind thing.
 * Be Quiet, Scooby-Doo! - Shaggy Rogers demands to know why he was the dope in Velma's mind thing.

Scooby-Doo Movies

 * Scooby-Doo on Zombie Island - After the credits, Scooby speaks to the viewer.
 * Scooby-Doo and the Witch's Ghost - At the end of the movie, Scooby speaks to the viewer.
 * Scooby-Doo and the Alien Invaders After the credits, Scooby greets the viewer dressed like an Alien.
 * Scooby-Doo and the Cyber Chase - After the credits, there is a seen where Scooby and the Mystery Inc. gang break the fourth wall and tell the viewers their favorite parts of the film.
 * Scooby-Doo! The Mystery Begins - At the end of the movie, Scooby-Doo winks at the viewer.
 * Scooby-Doo! Frankencreepy - During the credits, AlexSuperFan2112 points out some of the continuity errors of the film.