When a character looks at the audience and comments on what is going on in the work they are in, but does not explicitly acknowledge there is an audience.
One of the mildest forms of Breaking the Fourth Wall; often seen in works where the Wall is otherwise quite solid and it would seem odd for the characters really to acknowledge it. It's not even impossible for an Aside Comment to preserve the Fourth Wall entirely intact if the character is interpreted as talking to themselves (see Thinking Out Loud) or an imaginary audience. This type is sometimes done in a quiet voice (called sotto voce) to indicate that other characters cannot overhear what is said. Usually, the interpretation is left open unless there are other kinds of Breaking the Fourth Wall going on; it would be odd to say the least to comment on the matter if the Fourth Wall is solid, after all.
Sometimes used as a form of exposition where the character thinks out loud about what they're doing so that the audience will know, too; this can be done without even looking at the Fourth Wall, however. At other times, just used to deliver a punchline and/or snarky comment.
In a non-visual medium, where the characters obviously can't look at the audience, seeming to address the audience without making it explicit may suffice for this. However, the speaker visibly not looking at the audience disqualifies a piece of dialogue from being an instance of the trope.
Closely related to the Aside Glance, just taking it a step further. Compare and contrast with Fourth Wall Psych, where the idea of Breaking the Fourth Wall by addressing the audience is presented and then disproved. See also Leaning on the Fourth Wall.
Anime episode 298. While Ichigo is being shanghaied into making a movie, he turns to the camera and says "I need an agent."
Anime episode 346. Riruka Dokugamine says that wearing contact lenses makes her eyes dry out as soon as she puts them in, then turns to face the camera in a close up and says "It's because my eyes are so ginormous." (a reference to the large eyes of anime characters).
Academy Award-winner Tom Jones does this repeatedly. One time, when Tom is being chased by a jealous husband, he looks into the camera and shouts "Help!". Towards the end of the film, instead of just showing a crucial plot point unfold, one of the supporting characters turns to the camera and narrates the scene.
It becomes a Running Gag in At the Circus since Groucho does it numerous times. One of the best is a scene where he is trying to get something Pauline has stuffed down her shirt, and when he realized she's done so he looks at the camera in fear and says, "There has to be someway to get that money while staying out of the Hays Office!"
The Big Store: "This is a bright red dress, but Technicolor is SOOO expensive!"
After Sheriff Bart takes himself hostage, he retreats to his new office and says, "Oh, baby you are so talented...(looks into the camera) and they are so dumb."
When Bart hears the Waco Kid moaning in his bunk, he turns to the camera and says "The drunk in number two must be awake."
After boring the Waco Kid to sleep, Sheriff Bart looks at the camera and says, "I like to keep my audience riveted."
As two thugs assault a little old lady, she turns to the audience and asks, "Have you ever seen such cruelty?"
The theatrical variety is portrayed in The Assassination of Jesse James by the Coward Robert Ford: Robert Ford is the main character and narrator of his story. In the middle of a scene, he'll occasionally look at the audience and stage-whisper exposition. The artificiality of the trope highlights the inaccuracy of the plot.
Parks and Recreation was created by veterans of the American version of The Office, and includes the same "talking head" segments that both the British and American versions of that show used. However, unlike both versions of The Office, there's never any reference to a documentary being filmed and the crew filming the talking heads never impacts the action. In practice the talking heads function very much like Aside Comments.
The tv version of Lovejoy would have Lovejoy do this in a vaguely Shakespearean way, delivering either his internal snark, or a bit of trivia about the antique, as a way of showing how his thought processes worked.
The protagonist does this in both the British and American versions of House of Cards.
Malcolm in Malcolm in the Middle does this several times an episode, in order to comment on the goings-on around him or explain the background of certain events to the audience.
Doctor Who. Corrupt Corporate Executive Morgus does this in "The Caves of Androzani". This happened due to the actor misunderstanding the stage directions, but was kept because it gives the character an air of Shakespearean villainy.
Monty Python's Flying Circus: When Dr Larch says that his identity crisis as a psychiatrist drives him mad, Mr Notlob appears on a separate backdrop and says to us "A mad psychiatrist. That'll be new!"
This trope was very popular in Elizabethan theater, most notably in the works of William Shakespeare, who used it over and over again. Often it's even written in the stage directions.
Eugene O'Neill's Strange Interlude is famous for its frequent use of often lengthy asides. It inspired numerous parodies, of which Groucho Marx's in Animal Crackers is merely the most famous.
Parodied in Molière's play The Miser; the eponymous character's servant makes several aside comments to the audience, complaining about the guy's greed, but the miser hears this and asks him who he is talking to.
Happens in The Phantom of the Opera during "Poor Fool He Makes Me Laugh". The husband explains to the wife that he is going on a trip and leaving her with the maid, and as an aside "Though I would happily take the maid with me".
When Torg is being very slow on the uptake: "He'll figure it out any moment now folks!" (Unless you count "folks" as a direct acknowledgement of the fourth wall. It seems to refer to the audience, but it's left vague.)
In the episode "Bridle Gossip", Spike seems to be looking at the audience directly when commenting he can't come up with a pun from Twilight Sparkle's name.
In "Sonic Rainboom", both Rainbow Dash and Rarity say out loud to no-one in particular what they're going to do next at some point, but only on one occasion each do they look at the audience while doing so, demonstrating the vague relationship such comments can have to Breaking the Fourth Wall.
In "A Bird in the Hoof", Fluttershy gives an uncharacteristically cunning look to the audience and says "Always works!" during a Road RunnerShout-Out scene where she tries to feed a bird a pill by hiding it under some seeds.
In "Magic Duel", Trixie uses her magic to remove Pinkie Pie's mouth after she insults her by summoning a computer mouse and trashcan. At the end of the same episode, Pinkie goes past the screen fade-out demanding her mouth back, to which Twilight reopens the screen to give it back to her.
In "Keep Calm and Flutter On", after Discord brainwashes a colony of beavers behind everypony's backs, he turns to the camera and whispers, "Oopsie!" Immediately afterwards, when he announces he's moving in with Fluttershy, she looks towards the audience and mutters, "Oh dear."
1973/74 episode "Dr. Pelagian's War". Dr. Pelagian has captured Wendy and Marvin and is planning his next move.
Wendy: Marvin, we've got to reach the Super Friends!
Marvin: Sure. Any idea how?
Wendy: Uh uh. [Looks at the camera and the audience] Do you?
1973/74 episode "The Mysterious Moles". Superman is examining the cooling unit on the roof of the power plant. While talking to himself, Superman faces the camera and says "It's my hunch the thieves will try to lift this with a powerful crane copter."
Danger Mouse does this in "Penfold B.F." As he's in flight in his Mark III car and talking to Colonel K via his videophone:
DM: Just a second, Colonel, while I put the car into a bank...(veering slightly to the right)
Colonel K: Don't try it, DM!
DM: Why not?
Colonel K: You'll never get it through the doors!
DM: (to us, quietly) Good grief , I don't know why I bother.
"The Quake Threat". After Birdman destroys several of Dr. Kiroff's robots:
Dr. Kiroff: He's destroyed my metal men [turns to face the camera] but there's more than one way to catch a bird!
"The Brian Thief". When Doctor Shado sees Birdman approaching his laboratory:
Doctor Shado: It's Birdman, all right. He's finally arrived. [Turns and looks at the audience]] At long last!
"Meets Reducto". The title villain does this after completing his Reduction Machine Shrink Ray device.
'Reducto: With this Reduction Machine I will soon have this country, [turns to face the camera] perhaps the entire world at my mercy!
In The New Scooby-Doo Movies episode "The Ghostly Creep From The Deep" with the Harlem Globetrotters, Meadowlark tricks Curly into volunteering being the first watch while everybody else gets some sleep. As Curly marches, he turns to us and says "Sometimes I wish Meadowlark would learn to keep my big mouth shut!"
Young Samson & Goliath episode "The Colossal Coral Creature''. After the title monster shoves Samson down a chimney and puts his hands over the top, Samson looks at the audience and says "He's got the chimney blocked!"