Roomies also has the narrator directly interact with the cast. The plot device to explain this is he is a disembodied spirit of some kind. (Not to be confused with the other webcomic named Roomies, which evolved into It's Walky!, or the otherother webcomic named Roomies)
Of course, David Willis' Roomies briefly toyed with genre awareness as well, mostly for laughs.
In Monster of the Week, after Scully finally accepts that supernatural is real in this 'verse, both she and Mulder become Genre Savvy, recognizing the foreshadowing and commenting on how incredulous/stupid/weird this episode is. Summed up by Mulder once, when Scully started acting as if it was real life:
The Order of the Stick sometimes refers to lengths of time in "Strips", and the characters sometimes mention that their main purpose in life is to make jokes about the rules of Dungeons & Dragons. In an interesting twist, they also often display an awareness that they're Player Characters in a game of D&D. Which they're not, really, that's just part of the strip. This is your brain on fictional metafiction...
Belkar: Hey! If we don't stop the weepy melodrama I'm going to start dropping pop culture references, and I don't think anyone wants that!
In this strip, they plan to sneak in during the darkness, but have all day to wait. Haley invokes the standard RPG trope by declaring "Later, that evening..." and night falls.
In the collected edition, Dungeon Crawlin' Fools, one of the bonus strips has Roy siccing a dangerous monster on the Narrator (a guy with a microphone who'd been standing 'just out of the frame') to get them both out of their way.
In the volume, War and [XPs], a book-exclusive extra strip shows Julio Scoundrel's daring escape from Cliffport; Elan comments that it was pretty exciting "for a bonus comic!"
And in this strip, one of the characters realises that they're about to be attacked due to a sudden cutaway panel.
And then there's the time Haley climbed the sidebar of the strip's Web page so she could make her way to the illustrated cast biography and steal the diamond she she was holding in her profile, which has since been replaced with a note reading "I.O. Me One big-ass diamond".
In this strip, Sabine needs to explain to Thog how time can pass in comic strip panels.
And there's also the time when they needed to feed the monster in the darkness, and Belkar complained that he couldn't do it because "I told you that in one of the Dragon comics, so I'm not even sure if that's the same continuity..."
Don't spell Xykon's name wrong in your speech bubble. He can tell if you do.
Thog will always treasure thog's adventure with talky-man. it featured non-traditional panel layout.
Roy Greenhilt: What about the dozens of civilians you killed to lure them there?
Thog: actually, thog hazy on that. did thog kill them off-panel?
And the time that Tarquin realizes that that since he's talking openly about Malack being a vampire, that must mean it was already revealed to the heroes (and thus the readers); otherwise he would've been restricted to vaguely alluding to it even though everyone actually in the scene already knew.
Schlock Mercenary used to go way over the top with this, to the point of a character pulling aside an orange narration box to get a good look at a grisly wound, or a commander calling out an underling for her use of italics in the previous panel. The use has gradually reduced over time, though the narrator is still occasionally treated as a separate character.
The cartoonist also likes to show characters holding on to the panel borders when leaning into frame.
The "Attack of Bob" arc begins with George noticing the changed background color, realizing that it means the start of a new Story Arc, and panicking.
Also, it's an explicit law of the comic's universe that neither of the titular characters can die, solely because their names are in the title. So, when the omnipotent Fistandantilus attacks George, he circumvents this rule by changing the title to Bob: The Comic Strip beforehand.
In the Bob and George hosted Metroid: Third Derivative, Samus comments on the specific background music that accompanies fights with space pirates in all three Metroid Prime games (when you defeat all the pirates in the room, the music changes back to normal). Ie, "Music is fading, I got the last one".
Played hilariously in one strip of 8-Bit Theater, where Sarda demonstrates his omnipotent powers by rewriting Black Mage's speech bubbles.
In an earlier strip, the Light Warriors were trapped in a place where causality and space-time were twisted in on themselves, and could actually see alternate-time versions of themselves above, below, and to either side in other comic panels, and were commenting on each other's comments.
Warmage has built up a plot point around characters who gain "webcomic awareness". It's played as a serious dramatic point without any exploration of the nature of the medium, or the nature of fiction, not even a light-hearted Lampshade Hanging. The people who realize they're in a webcomic are still Genre Blind fools carrying the Villain Ball.
Fancomic Pokémon Yellow Comics has the main character pointing out whenever the color changes in different areas.
As one example from the many in the normal strips, in "Sluggy of the Living Freelance", there's a "MOOOO" sound effect after someone saying "What Could Possibly Go Wrong?" The characters wonder what it was and comment that it was probably supposed to be an ominous sound of thunder, and that the comic needs a new sound-guy.
Sometimes the characters look at a script as if they were the comic version of Animated Actors.
A one-shot guest strip had Riff discover that time was separated by "panels," and invent a device to travel between them. He accidentally hits Sasha with it and is very worried when she falls through the ground, but everything turns out fine when she falls from the sky thirty seconds later on the next row. Coincidentally, another guest strip on the same page also has the characters talking about and interacting with the panels, this time in terms of using a time machine to make them run backwards.
Debatably Epileptic Trees, there's a theory that Torg has a mild Medium Awareness - he's always the one to realise it's a guest week or the art style has changed, possibly tying in with the fact that he's stated to be unusually psychically sensitive within the strip's setting.
In the Insecticomics, the panel lines seem to be akin to dimensional barriers. Sideways (by virtue of being a sentient chaos virus), can just walk out of the panel onto the rest of the webpage, Kickback fishes for Vok with a fishing line extending past the bottom panel, and Override's cannon is so powerful that it blasts Dreadmoon and Thrust out of the comic entirely.
On this page of Rice Boy, Golgo's robot eye was able to see the speech bubbles from Rice Boy and T-O-E's conversation. One could interpret this as a way to show that the robot eye made an audio recording, but Word of God confirms the Medium Awareness interpretation.
1/0never really had a fourth wall to begin with (except when certain characters were given a fourth wall), but one moment that stands out as Medium Awareness is when they're messing with the camera angles due to the rule about not showing the jar and Marcus complains that nobody even knows he's there because of how short he is. Ghanny replies that they would if they've memorized the characters' text Fonts by now.
The first book of Erfworld was built around this trope in a sense. The main character Parson was pulled in from reality and is aware that it's a wargame, though while everyone else is aware of the rules, they don't get the context. If Parson understands that Erfworld has game-like rules, he still hasn't gotten the fact that he's in a webcomic.
The Fey in Keychain of Creation are explicitly aware that they live in a webcomic based around the rules of Exalted. This befuddles most of the other characters, who 'know' that they live directly in Exalted. In this case, it is because the Fey in the aforementioned game have an utterly alien mindset, and this was an easy way to represent that. The Sidereals seem to have a little bit of this too, with moves that rely upon breaking perspective and knocking people through the box boundaries - which is kind of what Sidereal Martial Arts normally do.
At least one XKCD comic references this. One or two of the early ones do it a way that could be seen as terrifying - the comic panels (and thus their whole world) begins to crumble and fall apart.
Art and Leaf of Apple Valley frequently make references to the fact that they are in a webcomic, something most of the other characters either ignore or don't notice. The author has justified that, since this is their fourth webcomic (following The Apple of Discord and two previous comics) they've more than had enough time to figure out what's going on.
In Problem Sleuth, Sleuth ends up attacking and destroying DMK's health bars directly, after he starts regenerating any damage taken instantly.
In various non-canonn side stories, the characters are aware that the story in question is non-canon. This is used not just for the occasional fourth wall joke, but also as an opportunity to have characters do things they wouldn't normally do because they're aware of the lack of consequences.
Weather Report: Highs today in the single digits... Matt: I'VE GOT YOUR SINGLE DIGIT RIGHT HERE, WINTER! Igor: (covering Matt's hand to prevent him from Flipping the Bird) Kids are reading this kids are reading this.
Dork Tower does this a lot. At one point, the characters even snark that the author is "as organised as a mound of wet marmots".
This page of A:TLA fan comic "Kyoshi - The Undiscovered Avatar" has troops fleeing the very panel they're in to the one below over the space between them from Kyoshi in the Avatar State.
Schtick-Shift: ...the hell do you think you are? Lucy: I'm the new Amazi-Girl. Robin:[from off-panel]psst, say it like it's a logo Lucy: What? Robin:like in comic books. say it like it's a logo Lucy: Robin, this isn't a comic book. You can tell because I'm a woman with agency. Robin:doooo eeeet Lucy: ...I'm the new AMAZI-GIRL? Robin:muy bueno Lucy: I said it the same way.
In this page of Subnormality, a ninja shuriken is essently made into an asterisk, which the characters use to read the note on the end of strip.