Frankenstein of Noblesse, when under the influence of the Dark Spear, which he summons willing whenever he can, as he's easily provoked.
Sapphire Gem, the zombie girl from Monsterful , an extremely random protagonist. In these twopages a nice example is given, there are a ton others though. She's also an Idiot Hero, and these two traits combined always lead to instant madness.
Largo from Megatokyo at first finds it hard to tell the difference between the real world and the videogame world. Then it turns out the Megatokyo world is indeed a conglomeration of anime and videogame tropes. Which just shows you can be Genre Savvy and a Cloudcuckoolander at the same time; in fact, it can be an advantage if the situation you're in is itself insane. Largo is just Crazy Awesome; which helps him in the insanity of the setting.
Every single character (save for Jame and maybe Liln) in Terror Island. Sid and Stephen (the main characters) are especially bad, what with the groceries and all that.
Stephen: It's strange how we have an invisible postal worker who delivers the mail by altering history so it was always here. Sid: We don't. We have a normal mailman who comes by before you're awake. Stephen: Same thing.
Red Mage is convinced his world runs on Tabletop Games rules. He carries around a character sheet, rolls twenty-sided dice to see if he succeeds at things, and is obsessed with manipulating these rules to his advantage. If he were in another webcomic, this would make him Genre Savvy. However, the world of 8-Bit Theater doesn't actually run on Tabletop Games rules; it runs on the Rule of Funny instead. That means he's just a Cloudcuckoolander, except when it would be funnier for him to be right. He's simply insane all the time, in his own special way, and often oblivious to logic, warping reality with his own bizarre ideas. Just because his crazy schemes occasionally briefly succeed (like the Chocobo breeding experiment) doesn't make him sane. You would never ever think of Red Mage as "the only truly sane person of the group".
Maybe during the earlier parts of the comic, before Sarda really started having an effect on the plot.
Fighter: D'you ever wonder if clouds see shapes in the ground? Because I wonder about that a lot.
Elan of The Order of the Stick. For instance, when Haley argues that, as they are adventurers, everything they do counts as an adventure... he takes off his shirt, covers himself in jam, stands on one hand, hangs a lantern from one foot, puts a squirrel on the other and plays with a paddle-ball with his free hand. And shouts "I'm on an adventure!" In an earlier strip, Elan found out that wearing armor incurs an armor-check-penalty on certain skills, including Hide. Therefore, he decided that removing all his clothes would increase his Hide skill to the point of invisibility. Hilarity Ensued. He much later concluded, when a newly resurrected Roy was standing naked in front of him, "You're invisible!" He also decided to say "Blah" 497 times in a row, just because it had never been done before. Elan is now less Cloud Cuckoolander and more hyper-Genre Savvy.
As of strip 889 Elan's genre-savviness has allowed him to break out of an epic-level illusion by recognizing that his cloud-cuckooland wishes had all come true, against all logic and reason.
Richard of Looking for Group is a combination of sociopathy in the vein of Black Mage from 8-Bit Theater and Cloudcuckoolander tendencies, bearing most of the humor of the comics currently due to Cerebus Syndrome.
Fluffmodeus, aka Little Blue Friend, in Something Positive, especially his first appearance.
"And and and and this other time? I was at the zoo and the man at the zoo was all 'You can't feed animals here' And I was all 'But why not?' And he was all 'Cause there's no one to feed 'em to.' HA HA HA HA HA HA HA HA HA HA HA It's funny, new friend! It's so funny! ...it only takes seven poundsof pressure to crack open a man's head... from the inside. Kisses now!"
Schlock Mercenary's Lieutenant Pibald turns into one of these when he forgets to take his medication, acquiring delusions of having hyperbolically exaggerated status or talents which he doesn't. This wouldn't be as serious a problem as it is if his hobby wasn't homemade explosives... that metastasize and form colonies.
Eddie from Emergency Exit. He is obsessed with traffic cones, thinks chickens are out to take over the world, collects distractions, and just generally acts like a insane seven-year-old on an eternal sugar rush. He also wields a Hyperspace Mallet, and uses a "coolness enhancer" that enhances whatever it's attached too. Anything. He also has a fully stocked Mad scientist laboratory, although the whether the stuff he makes is powered by science, magic, or some combination of the two is anyone's guess.
In UG Madness, Wizards of the Coast R&D director Mark Rosewater is portrayed as this. He's also an imp. The author claims this to be a true and accurate portrayal. Many who have read Mr. Rosewater's articles might agree.
Torg from Sluggy Freelance does this quite a bit, such as when he declares "I will find us a new place to live!" He doesn't actually make any effort to find a new apartment; he thinks making the big dramatic statement should be enough. Or when he promises to paint Zoe's apartment, and takes that as liscense to do a nude portrait of her on the wall of her living room. And doing a painting of Rodin's "The Kiss◊ on her bathroom ceiling. Using pictures of her parents as models.
Quilt from Dominic Deegan has no brain (he's a necromantic golem, a la Frankenstein's Monster), and thus can be a little... out there. When told to keep his eye on someone, his response was to take his eye out of the socket and point it at the subject. But this is probably where he exhibits the trope the most.
Lord Sykos from The Wotch is, as his name suggests, completely insane. Example: "Sorry, but no one goes anywhere 'til I'm done with my little investigation. 'Cept for you. You need to get me a taco. I don't know what they are, but I want one." His Perky Female Minion Aimee is pretty strange, too.
Jo in Cheer!!. Too ditzy to be fooled by the Agents' Someone Else's Problem Fields, completely Genre Savvy without even knowing it, and she thinks she's a Magical Girl. And talks to squirrels, which talk more like CATS. Also too ditzy to have been affected by Miranda's mind-altering magic, and thus retains all of her memories of being Colin.
Bass in Bob and George, very much unlike his video game version. He's not evil at all, and spends most of the comic wondering what's going on while staring blankly, and unlike Mega Man, never has moments of clarity.
The eponymous character of minus would normally qualify, dubbing herself Warrior Queen of the Ant People and wanting to grow up to be an elephant, if she weren't an omnipotent Reality Warper (with a dash of Nightmare Fuel Station Attendant) who ensures all her fantasies become reality.
Hugh, the CEO of Angst Technology fits this trope quite well, mistaking a monkey for a small child, singin hilarious mangled lyrics of songs during karaoke, and playing make-believe space cadet and western characters with the office supplies of canned air.
"We are men of vision. Like when Magellan crossed the Sahara, or when the Persians first made cheese in a can. We are living in an advanced age where man can look to the stars and walk on Uranus. I foresee a future for this company when our products are as popular as Frogger, or even... dare I say... Burger Time. It is our destiny, gentlemen, to forge ahead like Marcel Marceau and to take charge like that fellow Charles... who was apparently in charge. Look to the future men, for we may never see it again!"
Inquisitor Eastwood from Sonic40KExterminatus Now takes refuge in Cloudcuckooland sometimes when giantspiders show up. To protect his fragile brain from the shock, he has been known to begin calculating the number of teapots a walrus could eat while juggling George Clooney and David Hasselhoff.
Scary Go Round: Shelley Winters and Ryan Beckwith are like this all of the time, although their brands of oddness tend to vary. Shelley's detachment from reality seems to manifest in her bizarre thought processes, Ryan has his interesting grasp of history and both of them love a good non sequitur every now and then. As of the current moment, Ryan teaches school; slightly less odd, but then he is now a supporting character, and his students qualify.
Fletcher Apts: Kia is the cute ditzy girl who seems to be in her own world all the time, and any jokes told to her or aimed at her just fly right over her head.
Brad from Fur Will Fly fits the bill of a classic Cloudcuckoolander almost perfectly, complete with boubts of Fridge Brilliance. The sequel, Coming Up Violet, expands on the mahem with his doughter Beatrice, who is a chip off the block in almost every respect.
As one of the quotes implies, Leo from VG Cats has been known to go from "it's so hot out" to "there's a face growing out of my butt, if you touch it you can see the future" within seconds. This is when he isn't being a full-on idiot, though.
Buwaro from Slightly Damned due to a childhood that's best described as having nothing but brown rocks within many miles radius. His condition is currently improving.
The Cyantian Chronicles: Subverted and generally bent into a pretzel by Quinn Akaelae. She can actually teleport into another dimension and often speaks with two residents of said dimension, who can only be seen by her.
Rob from Rob and Elliot is this in the extreme. He talks to fruit, harasses Elliot for looking at his bum (as in hobo, not his rear) and trains dogs by threatening to kick them in the balls. He is always coming up with zany new schemes.
Sometimes, the Penny Arcadeworld, with one or two people who have been handed the Sanity Ball. Other times the world is sane and it's just Tycho and Gabe who are crazy...and sometimes it's just Gabe...and sometimes it's just Tycho...and sometimes it's Div...
All of the dream-selves seem to be this. Dave even forbids Jade from doing anything to his house while she's asleep (It Makes Sense in Context) because she tends to be so illogical when she's dreaming.
Any incarnation of Courtyard Droll/Clubs Deuce fits the description as well, in contrast to the rest of the Midnight Crew's harsher antics.
Terezi is...shall we say, a trifle eccentric. At one point she holds an elaborate show trial for a stuffed toy. Later, she responds to finding a friend's corpse by getting a number of other stuffed toys together to serve as her assistants and then doing a crime-scene routine. So her friend is dead and there she is pounding on his face with the arse of a stuffed dragon in order to dust for prints.
HorussZahhak is between this and just plain insane. He claims to be a horse trapped in a troll's body, later taking it to another extreme when describes it as a multiple system of several ancestral horse spirits. This would be fine,isn't were for the fact that he once rebuild Rufioh's body as a horse to be more like his ideal. Aside for that, he talks and behaves in a cheerful and even innocent manner.
Lee from S.S.D.D is a clone (most of which can't even talk) who can best be described as "flaky", and his tendency to stab himself with forks once his ability to feel pain is restored.
In fact he was chosen for a "special assignment" because he was too mentally unstable to be a regular soldier, the rest of his squad have their own problems ranging from plain stupidity to suicidal depression.
Yuki from Ménage ā 3, though lampshaded by the fact that growing up around her father's comic art really did mess her up pretty badly.
James from What Do You Do takes this Up to Eleven; he once stops his party just to build a stone walrus, which he then levitates and uses as a mount. Really, the whole comic takes place in Cloudcuckooland.
Coyote from Gunnerkrigg Court shows signs of this and Large Ham. Annie also has elements of this, often seeming to occupy a separate world to her classmates, and the pair definitely rub off on one another.
David from Bittersweet Candy Bowl is all the way up there, as his first conversation with his admirer, Kizuna, shows:
Arkady from FreakAngels, due to an overdose, is quite flighty, but certainly seems to be perfectly in control of most every situation and the only one willing to push her powers beyond their assumed limitations.
Girl Genius: Certain Jägermonsters are this, interestingly enough. Or not, considering their creators. Whether or not it's interesting that they qualify, they certainly are interesting guys either way.
For what it's worth, Sparks can definitely head into this territory.
Bliss from The Adventures of Wiglaf and Mordred. And to top it off, only one person can hear her speaking as she rambles on about colour theory, how a combustion engine works or something else with no relevance to the topic at hand.
Archipelago gives us Blitz. He's a bit of a tragic case, as he's a man-child whose mind was badly broken in the same incident in which his eye was gouged out, but with that aside, he's a happy-go-lucky overly optimistic sidekick who is the poster child for Attention Deficit... Ooh, Shiny! and goldmine for humor.
Mirth from Voodoo Walrus is a prime example of this. And for good reason too. Arguably, the same could be said for Grymm as well, but not on a full time basis.
Several examples from Survivor: Fan Characters, including Craig, a fourty-year-old maniac who thinks he's a strategic mastermind Kala, a Wolf Girl who speaks to inanimate objects such as her "Happystick", and Gatemaster, an oaf who controls the entire season without even realising it.
Reece in At Arm's Length. Her train of thought frequently gets derailed at the station. She's known to focus on non sequitars during an action scene.
Everyone in Edmund Finney's Quest hails from Cuckooland, except Edmund himself, who is the Only Sane Man on the planet. For example, Edmund meets this nutjob while traveling with a pair of hunters with "Nice To Meet You" guns, who are trying to find a Yeti using only a coffee stain and an extraordinary misinterpretation of some guy's comment about a sandwich.
Bunny of Blade Bunny is a hyperfocused killing machine in combat, otherwise she is oblivious to social nuances.
While his name and Character Title implies he's more of an Idiot Hero or perhaps The Fool or The Ditz, StupidFox isn't stupid so much as just weird, having shown flashes of creativity, learning, and insight, but going about it all in a charming, yet slightly surreal way. The strip's MST3K Mantra looks to be "It probably makes sense to him."
In Manly Guys Doing Manly Things, both Canadian Guy (much to the Commander's ire) and Jared (who the Commander is more tolerant about, considering he finds Jared's brain bizarre and interesting).
Shiitake from ''Negamaki!'' spouts odd statements at random, agrees to be sacrificed to a dark god with very little encouragement and has a casual conversation about the movie Event Horizon with said dark god.
Later comics have him citing that he uses naive wonderment to avoid thinking about things, possibly making his tendencies towards this trope a defense mechanism from the weird, traumatic things his friends rope him into.
Tempura Potato seems to be one of these, rambling and singing all the time, but it's mostly because he's strung out on cough syrup. Reality breaking apart suddenly makes him lucid.
Zedfelos from Final Destination Pixelation. As described by Zymeth,
Zymeth: Trying to delve into the inner machinations of Zedfelos's mind is like trying to deep-water-dive without proper protection...the pressure begins to build up and you are eventually crushed by the sheer magnitude of the force of your own weight.
A number of characters in Princess Chroma are off their rockers, but Sonny, who advises June to use cheat codes to win real-life battles and pulls a cork out of thin air to plug up a magical cannon, takes the cake.
Devin of White Dark Life has an overly active imagination and poor understanding of how the world works leading to some pretty odd conclusions. Vomit from over eating? Dark Matt has control over her vital organs. Aliens take a hostage? give them what they want for space cookies. Sadly, this whimsical side slowly edges out of her life as she grows older and understands how horrible her life has been. Once she becomes an adult it's gone entirely having been replaced pessimism and anger.