Cysero from many of the Artix Entertainment line of games (AdventureQuest, DragonFable...). While very coherent and attentive to a problem at hand, he often slips into Cloudcuckooland, which inevitably means something weird is going to happen or is already in the works when he gets involved. Naturally for a guy who once used a black hole generator to stretch spaghetti and has a wizard's tower infested with Dirty Laundry Golems, the Alice in Wonderland parody in one game casts him as the Mad Hatter.
The Staff member the character is based on can be as big a Cloudcuckoolander at times, though whether or not this is his real personality or him acting like his ingame counterpart is unknown. As an example, at one con the team went to, he gave socks out to random fans and wore the bathrobe from Artix's hotel room to their panel.
Korin, from Mechquest, never seems to understand what's going on, he wears a paper bag over his head at all times, and although completely omnipotent, he doesn't really want to do anything at all to help save the world. Luckily, he isn't evil, so you don't have to worry about him going against you.
Subverted in Psychonauts: Shegor appears to be a Cloudcuckoolander under the delusion that her kidnapped pet turtle can talk and has the answers for everything. When you finally rescue her turtle, after it just sits there for a while... it actually does start talking and its plan does solve everything — at least for the moment.
But also played straight with... well, about half the cast, give or take.
Naturally, it's a game about psychics and their line of work of entering people's minds, since the campers have...hilarious quirks, and most of the adults have Dark or Depressing backstories, it's to be expected.
Leliana and Sten from Dragon Age: Origins. Leliana believes that she is on a journey from the Maker, and if romanced, describes your eyelashes as being like butterflies she wants to catch and keep in a jar. Sten tries to understand your dog's inner nature by engaging in a contest of growls with it, and at the end, proclaims him "worthy of respect". Sten at least is from Cloudcuckooland (he is a staunch adherent of the Qun, which is a Blue and Orange Morality philosophy from the perspective of Ferelden and the player). Leliana, based on the other Orlesians in the game, has no such excuse.
Sten believes the entire Ferelden people are this, due to their unconditional devotion to their Mabari Hounds, which makes up a great deal of their culture. If the Warden is imprisoned at one point in the game and Sten and the Dog are chosen to rescue them, he starts to converse with the Dog, before realising what he's doing;
Merrill the Dalish elf blood mage from Dragon Age II. She often blurts out ponderings that have nothing to do with anything (such as how qunari scratch their heads, or whether Isabella has a peg leg and an eyepatch when she's standing right next to her and can clearly see that she doesn't) and has absolutely no concept of ordinary social graces. Varric and Isabela adopt her as a Morality Pet. Varric even gives her a ball of string, so she can leave a trail and find her way home, after she gets lost on the way to the market and ends up in the dangerous slums. Again.
She's also ended up in the Viscount's bathing chambers, and knows how deep the harbor is because she's fallen into it.
If romanced, it's mentioned that she often ends up wandering into other people's gardens, picking flowers and playing with the guard-dogs. Apparently Aveline regularly has to get the charges of trespassing dropped, while Hawke has taken to paying off a lot of their Hightown neighbours and their guards, in attempt to keep the peace.
The legendarily bizarre ranger Minsc and his "Miniature Giant Space Hamster" Boo from the Baldur's Gate series.
Edwin is seemingly his Evil Counterpart, a self-important wizard with a strange obsession for calling everyone monkeys, and constantly talks to himself in such a way that everyone hears him - and is shocked that people can do that. Interestingly, these two hate each others' guts. Though that has less to do with their different varieties of Cloud Cuckoo-ness and more to do with Edwin being a Red Wizard of Thay and Minsc being a warrior of Rashemen — the Red Wizards are seen as monsters in Rashemen and most of them, including Edwin, live up to that reputation.
Edwin won't stop mocking him about the death of his witch in the second game.
Jan Jansen has a long, rambling, nonsensical story involving either him or one of his many, many relatives for every situation. Some of his lines border on Painting the Medium (like talking about how ever since he was a kid, everyone he sees would glow bright red at night, which is how the game depicts Infravision for the player.)
The only situation he doesn't have a story for is when the party is sent to Hell.
GLaDOS , despite being an all-powerful AI, seems to have a very loose grip on reality. She regularly makes childish insults at the player in later portions of the game and tries to convince you that one of the puzzles is impossible to test your resilience in an atmosphere of "extreme pessimism". She also instructs you to take the infamous Weighted Companion Cube (a box with hearts on all its sides) with you on one of the tests, then asks you to euthanize the inanimate object at the end by dropping it in an incinerator. And guilt trips you over it.
Cave Johnson, founder of Aperture Science. A man with no practical understanding of science, his inventions are nothing short of insane and counteractive to whatever purpose they were designed for, which isn't helped by his enthusiasm for pointless experiments and SCIENCE!.
Space Core: Space?! SPACE!!! (launches itself through the portal leading to the Moon)SPAAAAAAaaaaaaa....
The Fact Core could probably qualify as well.
Fact Core: The square root of rope is string. Cellular phones will not give you cancer. Only hepatitus. 89% of magic tricks are not magic. Technically, they are sorcery. Error. Error. Error. File not found.
Justice for All has Regina Berry, who demonstrates that a Cloudcuckoolander can be the cause of tragic circumstances in a (mostly) realistic setting. Due to being raised in a circus, she has a fairly substantial disconnection from reality. She doesn't understand, for example, how her putting pepper on Bat's scarf led to him being bitten by a lion... or that he may never recover from the resulting coma. Bat's brother, Acro, was so infuriated by her lack of remorse that he decided to kill her.
The whole series is chock full of less tragic 'landers, including Maya Fey's laughably bad grasp of technology, Ema Skye's utterly bizarre "scientific theories", and Trucy Wright (who had a rather... interesting exchange about how 'Revolver' and 'Wonder Bar' sound the same).
The Judge, whose grasp on reality is just firm enough to give the right verdict every time — but no firmer.
True to her role as a lawyer-sidekick-girl in this series, Kay Faraday is often putting Edgeworth's nerves to the test. Interestingly, she's also the only side-kick girl among the four (Maya, Trucy, Ema, Kay) who's actually incompetent at her "occupation of choice", information-theft, probably in order to make up for Edgeworth's hyper-competence.
Ini Miney in case 2-2 slept through a murder, and testifies that when her dead sister walked into the room, she had a rather dull surprise to her being there. She's actually Obfuscating Stupidity.
It's safe to say almost anyone who is not the player character will have some degree of the trope.
Manah in Drakengard, when she's not trying to be actively evil, has all the charm of a cute little girl playing with imaginary friends.
Aldanon in Neverwinter Nights 2 is a wizard equivalent for the absent-minded professor stereotype, exhibiting qualities like lapsing into rambling doublespeak with metaphors abandoned halfway, changing subjects mid-conversation, forgetting his own orders, or mistaking a prison cell for his own house.
At one point, he begins listing off a number of RPG tropes that he claims your team will have to perform, complete with "reforge the broken key" and "acquire some rare, arbitrary items." Only to be almost immediately shot down by one of his servants, who he had commissioned to do the exact thing he supposedly needed the arbitrary items for. Then he congratulates himself on a job well done.
Grobnar is another example, he is a gnome bard with a tendency to go off on tangents about his mouth and his codpiece and with a lifelong quest to find supposedly deific beings known as Wendersnaven that are apparently undetectable and all-powerful.
Sheogorath, the Daedric Lord of Madness from The Elder Scrolls is obliged to follow this trope.
"I've been waiting for you, or someone like you, or someone not like you."
"Well, looks like the cat's out of the bag now... who puts cats in bags, anyway? Cats hate bags."
"But enough about me. Let's talk about you. I could turn you into a goat. Or a puddle. Or a bad idea. I could make you eat your own fingers. Or fall in love with a cloud. Perhaps... I could make you into something useful."
"I once dug a pit and filled it with clouds... or was it clowns?... Come to think of it, it began to smell... must have been clowns. Clouds don't smell, they taste of butter. And tears."
Many other characters in that expansion could fit the trope. For example, Big Head, once you give him the Fork of Horripilation he was searching: "Happy day! Happy day! The blind shall see! The lame shall walk! The short shall tall! Forks for all!" Considering that the Shivering Isles is Cloudcuckooland, this is hardly surprising.
M'aiq the Liar is a Khajiit who delivers cryptic Take Thats to the player when they talk to him. Many of his statements make absolutely no sense In-Universe, making him appear this trope.
Riften's court mage Wylandriah in Skyrim is an especially bad case of this, as she keeps launching into non-sequiturs, rambles on about pseudo-magical things without realizing they make absolutely no sense whatsoever to anyone else (even other mages!), and somehow has the ability to "misplace" items from her laboratory across half the country, often in places that someone like her would normally have no business being in the first place. Surprisingly, she hasn't blown anyone or anything up yet... although a few NPCs fear it's only a matter of time before she accidentally transports Riften into Oblivion or something.
Cicero in Skyrimseems like one of these at first...but not only is he a lot more competent and dangerous than he looks he singlehandedly almost kills the rest of the Brotherhood when they finally push him too far, he is also completely right about how unwise it is for the Brotherhood to stray from centuries of tradition.
Arguably, everyone else in the damn game has a tendency to dip into this, the creator of the above mask decided that making a mask blink is more important then making the mouth move, Naked Snake discussing how being in the box brings inner happiness, among other things.
SIGINT will actually ask if he's the only normal one around.
Bianca, your childhood friend-turned-rival from Pokémon Black and White. N comes off as a little loopy before you start to learn who he really is... and after. Justified; both of them have... questionable home lives and are quite sheltered. N is also clearly abused.
Rhyth/Mew from Jet Set Radio is definitely this; she always has something random or just plain strange to say, such as
"I love everything about Tokyo-even the things I hate."
The Touch Detective games has Penelope. A banana loving girl who is a Cloudcuckoolander to the point that her very hair is soft and fluffy and cloud-like. A good example of her air-headedness is displayed in a conversation between protagonist Mackenzie and shopkeeper Daisy.
Daisy: Well, she's been pretty quiet lately. But, I really didn't give it any thought. I mean, it's Penelope. She could wake up and say, "I'm not talking today!" Mackenzie: She's done that. In fact, she didn't talk for a week. Daisy: Really? Even to herself? Mackenzie: Well, she pantomimed to herself. Daisy: She pantomimed to herself!? She's madder than a hatter.
Flonne from the first game, though smarter than she looks, is also more than a little out there. For example: In Disgaea 4, she blows Artina's cover in a casual conversation, despite Artina having explicitly asked her not to use her real name while she was at work. And this happens literally minutes after she makes her appearance.
Charmy Bee from the Sonic the Hedgehog games. Somewhat justified in that he is a hyperactive 6-year-old.
Charmy: Oh, flower, pretty flower, show your face and I'll sting you!
In context, that quote is one of his lines for when you find a giant purple teleporting flower in Sonic Heroes, which are activated only by Charmy's stinger.
Bean the Dynamite (a green duck who uses bombs), though in the actual games he only appeared in Sonic the Fighters and Fighters Megamix and thus didn't actually get any known personality in that continuity, is often portrayed as this by fans (and later the comics).
Some of the villagers in the Animal Crossing games tend to be like this — particularly the villagers with the "lazy" personalities. For example, the following conversation between two villagers in City Folk:
Jeremiah: ... growwwlll... (Jeremiah's Catch Phrase at the time) Lobo: Oh no. Jeremiah: I wonder... would a crowbar taste better if you soak it in soy milk first? Lobo: ARGH!
And speaking of Lobo, he and others of his personality sometimes compare looking at a model of a room to looking into someone's home through the window. Lazy-type males still hold the crown, though, with Big Top once deciding that a snail's classification was "food" (on the basis that snails were delicious). In context, he was asked what it was if it wasn't an insect, and came up with that response.
Arcueid from Tsukihime has a mild case of this. This only applies to her game character, however, since her anime counterpart lacks this and is therefore far less lovable. In the Carnival Phantasm anime, where she's more like her game self, she is the only character not subject to Character Exaggeration or Flanderization. She is quite accustomed to crazy things happening around her.
Psymon Stark from the SSX series. Apart from a noticeable facial tic, Psymon's... condition is just that; He's had a long history of mental illness ever since he tried to jump some power lines on his bike. His in game dialogue only makes his lack of lucidity all the more apparent, with lines like "Knock knock who's there!?" and "Oh sweet, sweet pain...", and his gold medal cutscenes show him yelling things like "You're all crazy!" or "Hurt me, hurt me!" Overall, he's a natural disaster just waiting to happen, and spectators, competitors, and event organizers alike all anxiously watch Psymon compete in fear that this is the year he'll go too far. Oh, and his signature move, the Guillotine, is so suicidally dangerous (as you might expect from the name) that you'd have to be crazy to even think it up.
Sakura, with most of her victory quotes, such as asking Chun-Li if they could switch outfits for a day for fun. After beating the snot out of her.
Rufus, with his victory quotes often being nothing but random ramblings about his life, confusing opponents for Ken or occasional Lampshade Hanging on character traits like Chun-Li's hips. Again, after beating the snot out of people.
The Soldier of Team Fortress 2 fame acts like this a lot. His version of history includes the dubious fact that Noah was actually Sun Tzu, the animals were bought via fight money, and after they were on the boat, Sun Tzu beat them all up. ("And from that day forward, anytime a bunch of animals are together in one place, it's called a zoo! ...Unless it's a farm!") This was discovered during a Drill Sergeant Nasty speech to a collection of severed heads. He also joined the World War 2 effort - stopping in 1949 only after hearing that the war ended. But then, a lot of the cast goes into this a little; the Heavy is under the impression that both his BFG (lovingly called Sasha) and sandvich are people, and talks to them a lot.
All of the characters in Team Fortress 2 are disturbed or insane in some manner, but the Soldier does seem to have the weakest grasp on reality and also personifies this trope with his rapid changes in subjects. Further evidenced in the War Update, where the reason he is fighting the Demoman is because he managed to get fooled by an obviously faked message using the Demoman, in which he apparently reveals the Soldier's status as an actual civilian. Even after acknowledging that the voice sounds robotic, he still buys what is said.
Also from the War Update, the Soldier's new domination taunts are very telling of his state of mind. He has a number of taunts where he refers to the Sniper as "Bilbo Baggins" or some variant (the joke being that Sniper is Australian, and Lord of the Rings was filmed in New Zealand).
The reveal from the comics that Sniper actually is from New Zealand can make this an example of The Cuckoolander Was Right.
Expiration Date takes it up to near-Talkative Loon levels. Among other things, he takes a bizarre glee in putting bread in the teleporter, and, for no obvious reason, wants the Spy's idea bucket.
The Pyro; nobody has a clue what he (or she) is saying, but he wears a number of odd hats (including a propeller beanie and one of the Engineer's rubber gloves), wields weapons like a rake and a mailbox, and "Meet the Pyro" shows he views the mayhem he creates as him blowing bubbles in a cutesy Sugar Bowl full of diapered cherub versions of his enemies.
You could make a case for the Mr. Saturns in EarthBound and its sequel. Their grammar is off-the-wall and punctuated by words like "boing" and "zoom", they have a tendency to say odd things like "Dakota" and "rice paddy" apropos of absolutely nothing, the font they speak in looks like a young child's handwriting... one in Mother 3 busied itself by staring at the ceiling.
Moe in Da Capo has issues. Apart from sleepwalking to school while playing the xylophone (yes), being obsessed with hot pot and being very disconnected in general from life around her, she is apparently convinced kisses are supposed to taste like lemons, so she eats a lemon drop right before kissing Junichi in her route.
Agitha of The Legend of Zelda: Twilight Princess probably classifies. She's the self-proclaimed Princess of the Bug Kingdom, is seemingly ignorant of the fact that most people have no particular desire to bathe in snail slime, and demands that the Legendary Hero Chosen by the Gods go fetch bugs for her ball. Oddly enough, she's one of the most popular NPCs. And apparently, she cheerfully chats with wolves, in a world where most people just run. While referring to them as puppies.
Let's not forget the infamous Tingle. He's a middle-aged guy who dresses in a skintight green outfit in order to emulate the "fairy boy" (Link). He's obsessed with Rupees, he flies all over the place using a red balloon, his Catch Phrase is "kooloo-limpah", and he forces his brothers and employees to dress in outfits similar to his. There's a very good reason why he was in a jail cell on Windfall Island in The Legend of Zelda: The Wind Waker.
Colette Brunel from Tales of Symphonia often falls under this, especially during the skits.
Regal: Why does the subject of the conversation seem to go out the window when talking to Colette?
Or during post-battle dialog.
Sheena: And don't come back! Colette: I don't think they CAN come back. Sheena: You're becoming more like Lloyd, aren't you?
Pascal from Tales of Graces From her appearance to beginning and end of game baffles the entirety of the party.
Kirby! He's just a happy-minded person who always thinks of food and sleeping. Particularly notable is Kirby Squeak Squad, where Kirby only saved the world because his cake was missing. There's also Captain Waddle Dee, who works for Meta Knight...
Axe Knight: Kirby is moving along the base of the ship. Captain Vul: Not much we can do to him there... but the wind is strong. Waddle Dee:And it's cold.
Final Fantasy XIII gives us Vanille. Whether she's molesting sheep for their wool, cooing over Chocobos, or skipping around acting like a sugar-high idiot, she never seems to be much of anything beyond this trope. By midgame, it becomes apparent that while this may have been her personality 500 years previously, at present time it's mostly just an act to keep her Stepford Smiler facade unnoticeable to the rest of the party, especially Fang.
The Suffering gives you a drugged-out and half-naked teenager out of his mind, begging you (who he thinks is his father, in his overdose-laden delusions) to protect him and help him to safety.
Moira Brown in Fallout 3. She apparently thinks digging a well with a miniature nuclear warhead is a perfectly fine idea, among many other zany ideas. There is a quest line in the game involving the Player indulging her cuckoolander propensity. You can also convince her to stop. You Monster!. She is actually an incredibly smart person with more of a passing relationship with normal. You can find this if you hack her comp "Q: How to prevent raider attack. A: raider would not sit down for an interview". Despite that, she very well knows just how important the entire records of a library are, and how to make use of the knowledge.
Ellis' Cloudcuckoolander status is especially apparent in Dark Carnival, where he expresses great displeasure that the survivors cannot go on any rides. In the middle of a Zombie Apocalypse. In an amusing turn of events, In "the Passing" Ellis suddenly becomes VERY concerned about how he appears to others. In particular, Zoey.
"Ellis is a mechanic with a love of life, a firm belief in his own immortality, and the ability to treat any setback as a fun dare to impress his friends.... Then the zombies had to go and spoil it. Now Ellis is looking for new things to occupy his time, and finding plenty. It turns out the zombie apocalypse is one big dare, and thereï¿½s no shortage of crazy stuff he can try to impress his new buddies."
The Truth from Grand Theft Auto: San Andreas clearly rambles in a style suggesting he's mad, but at the same time, seems to know a great deal about things not obvious to CJ. He's also a stoner. And he apparently got high with some really awesome polar bears.
Persona 4 has a minor NPC, appropriately described as a "Spacy Girl", who sometimes pops up in the Central Shopping District and the Samegawa riverbank. Some fans have likened her to Osaka.
BlazBlue has the EVER so flighty Taokaka, resident cat girl. She often breaks the fourth wall by slamming directly into the screen, staring at the player, and can celebrate winning a match by patting her butt or running away and slamming right into a pole that strangely wasn't there before...
Steven Heck from Alpha Protocol fits this well. He nearly poisons his associate with dry-cleaning solution because he can't remember where his keys are, asks a security guard about TV cooking shows before killing him, writes the single longest rambling sentence in existence in an e-mail, builds a mini-gun on a subway car "just because it might be useful later" and thinks the protagonist's middle name is "Finnegan", because a minotaur told him this when he got stoned. Although he did doubt the logic of the minotaur's argument.
Many of the lines said by Et from Mana-Khemia 2: Fall of Alchemy are out of context with the current party's conversations. Goto and Pepperoni also fit this trope to some extent, but at least they manage to say something coherent.
While the cast of Touhou qualifies to some degree, Yuyuko is out of touch with reality even by the series' standards, as well as an Obfuscating Stupidity version of this trope. She seems to do everything based on whimsy or her base needs and also seems to have a hard time paying attention to what's right in front of her or how others are reacting to her. It really doesn't help that she has been slowly losing her memories over the past millenium. She's sometimes shown to be extremely smart and perceptive, though. In both Imperishable Night and Ten Desires, she's shown to have figured out exactly everything since the beginning, and in the Spin-Off manga Silent Sinner in Blue, she manages to troll Yukari, of all people.
Another "even by Touhou standards" candidate would be Kotohime from the PC-98 game Phantasmagoria of Dim.Dream, whose primary character traits were compulsively collecting random stuff and being delusional and thinking she was a police officer. Her danmaku abilities are never explained. She also displays the "uncanny understanding of the plot" aspect, as her victory quote to Chiyuri is to start reciting the Periodic Table of the Elements (despite living in Gensoukyou, where magic reigns supreme and science is heresy), and she recognizes the electrical equipment in the hypervessel.
Being a Cloud Cuckoo Lander seems to be an inherent aspect of living in Gensoukyou. When Sanae, a human that was transported to Gensoukyou, was introduced in Mountain of Faith she was fairly reasonable, but by Undefined Fantastic Object and Hisoutensoku she was as unstable and unpredictable as everyone else, as well as being upgraded to player character status. Gensoukyou: the land where common sense is a weakness.
Moriya Suwako often gets this treatment in fanon due to her bizarre fighting style in the fighting games and that she fights the player character out of boredom in Mountain of Faith.
Komeiji Koishi is, as noted by another character studying her danmaku, apparently airheaded and prone to saying random stuff. This is later revealed to be because she's essentially an Empty Shell due to closing her third eye; while she can talk and interact with people, all her words and actions are performed entirely subconsciously, and she no longer has a real personality or desires.
The Spin-Off gag manga Inaba of the Moon and Inaba of the Earth shows Kaguya Houraisan to be one as well. She frequently comes up with strange ideas in her spare time (and got bored of them as easily, too) and doesn't seem to think much of abusing the Earth Rabbits...or Reisen. In one instance, When her Arch-Enemy Mokou challenges her for a duel, she ignores her completely and asks for tea.
One person in particular has Patricia Tannis, former Dahl scientist who after spending quite a while on Pandora has become part this and part Ax-Crazy, though is still pretty calm about it. Her journal entries show her descent into madness as she develops a relationship with her recorder (they're just friends now) and instills a personality into the corpse of a bandit she killed (his name is Leslie and he turned to violence due to being mocked for his name). After collecting her entries for her, she requests for you to bash your head in with a rock to forget everything you heard.
Tannis returns in Borderlands 2, claiming that she ate a Siren's hair out of scientific curiosity, and that it tasted like fried pickles. The game also confirms that Tannis has Asperger's Syndrome, which barely explains half of her madness.
One of Roland's allies is Tiny Tina, a happy-go-lucky Creepy Child with a fondness for explosives. A side quest sees Tina holding a tea party with guests such as a large jar with a top hat and monocle on it and a larval varkid stuffed inside, a doll with a hand grenade for a head, and a bandit who sold her parents out to the Hyperion corporation, whom she gleefully electrocutes to death.
The DLC pack "Mr. Torgue's Campaign of Carnage" has the eponymous Mr. Torgue, founder of the Torgue Corporation who's obsessed with explosions, action, and manliness.
Psychos, as the name implies, constantly babble on about puppets and Bicycles made of meat. One of them is even available as a DLC player character, Krieg the Psycho, although he subverts the trope by having a completely sane inner self who has no control over his actions.
Dwarf Fortress: the only game in which being on fire is cause for a good drink.
Dwarf psychology works like this: My wife and child were killed by serial murderer elephants and the fortress has been attacked by a beast lost to time, but I'm happy because that dining room was really nice.
Sonny Joon, The Unseen from the Nancy Drew game series, is probably this trope, to judge by his coatimundi phobia, UFO obsession, and generally weird doodles. Rentaro from Shadow at the Water's Edge shows signs of this too, particularly when he's gushing about his love of numbers or mimicking the expressions of deer.
Herbert Higginbotham from LittleBigPlanet 2 qualifies. Most of what he says makes very little sense. Even after he's cured of a mental illness, where he ranted just as nonsensically and ate everyone's socks.
"There were these geometries, these fractal star-worms, and they were competing for my affection, and they were amazed when my eyes... were pies, and they were spinning, and cooking, and dancing in figures of eight."
In BioShock, there are about half a dozen denizens of Rapture with even a tenuous grasp of reality, and whimsy and delighted singing are common. One of the few examples where this is used to make things creepy as fuck.
BioShock Infinite gives us Robert and Rosalind Lutece, who talk like Tweedledee and Tweedledum, give very cryptic references, and are seemingly quite insane. They are genius physicists, and responsible for the entire plot; but they're also technically ghosts and are permanently out of sync with both time and probability in our universe. It's not too surprising they are kinda confusing.
Bella from The Color Tuesday is... a bit odd, generally acting like a lady of status from the 18th century in a game set in a parallel of the 20th. Her pretentiousness pisses Alex off no end.
Yukari in Kara no Shoujo worries about koi drowning, has a great love for bugs and uses them nonchalantly in cooking.
Archmage Rakorium from Drakensang is probably the craziest and most powerful wizard on Aventuria. He's constantly absent-minded, has an irrational hatred for reptiles of any kind and turned a whole band of brigands to stone because he believed they were dragon worshipers.
Riko in A Profilehates being serious. She gives pretty good advice, but she's also prone to telling her step son to be careful not to impregnate his stepsister out of nowhere though she supports the relationship entirely.
Rin rivals Osaka for sheer out-of-touch-with-reality-or-possibly-just-on-a-different-plane-of-it-ness. "The problem must be in your pants!" Unlike Osaka though, Rin is fully aware of the fact her mindset is seen as out-of-touch, she just doesn't let it stop her. The ending scene for her Act 1 route is even titled "Clouds In My Head".
Rin: ...So that's why I'm trying to figure out if there is something I need to figure out and then figure that out before it's too late and all hope is lost.
Utterly demolished in her route. Later scenes show that her eccentricity isn't always funny or cute, and Rin herself proves to be frustrated and discouraged with how people can't understand her thoughts, whether through words or through her art. Hisao often struggles to keep up with her train of thoughts, and sometimes gets extremely angry at her.
In Hatoful Boyfriend, we get Oko San, a bird absolutely obsessed with finding the "perfect pudding", and Anghel Higure, a bird who believes himself to be a fallen angel and the heroine to be his reincarnated lover Edel Blau. Anghel's madness is actually justified later on when it's discovered that he secretes hallucinogenic pheromones. And in Holiday Star, where he may be a Reality Warper.
Brother from Final Fantasy X-2 is about as weird as they get. Not only does he say outlandish things, he's almost always dancing in place or flailing his limbs while talking.
Nine Hours, Nine Persons, Nine Doors has Junpei, arguably. Some of his thoughts and responses can be REALLY out there ("Apologize to funyarinpa!"). June sometimes has some weird moments, too. You could say she has the excuse of being a walking supernatural phenomena. Actually, when you consider that they can still find the time to make lame puns in the midst of a dire situation under a strict time limit, the entire main cast probably counts.
Azuregos falls in love with a Spirit Healer. Budd...just...anything with Budd present. "I'M A MANATAUR!!" anyone? Harrison...every single quest he gives, especially the one where he pointlessly destroys an ancient Egyptian-like temple.
Tirion Fordring might not seem like one at first, but...the guy makes you fight and kill his own people, unrestrained monsters, and demons in his own personal Thunderdome for no apparent reason. He also makes you "beat each other with pointy sticks" aka joust, quite possibly the most hated quests in the game. In another example, the guy also puts two people who won't hesitate to try and murder each other (Garrosh and Varian) within a few feet of the other one while observing his special games. He claims this is to promote peace, but he has an encounter that does exactly the opposite with your faction fighting the other faction, for NO REASON AT ALL! Perhaps his Trauma Conga Line messed with his head?
Double H from Beyond Good & Evil is a former military officer who constantly quotes from the military handbook and doesn't seem all that right in the head. Justified, as when you finally meet up with him, he's been in a Domz torture device for several hours and claimed that his brains feels like jelly. Though there are some signs that he was like that before the torture, like having apparently begun the infiltration mission he was captured on by swimming half a mile in full body armor.
Lulu the Fae Sorceress from League of Legends is a young yordle girl with a boundless imagination who went off to play with with the fairies for several (hundred) years and learn their magic. Upon returning to normal life in the rest of Valoran she's completely cuckoo, albeit adorable, and talks in nonstop nonsense. "Never look a tulip in the eye!"
"Yup! That tasted Purple!"
Agent York from Deadly Premonition. When the game itself describes him as having a "surreal demeanor," there's little doubt that he's a little off-beat. He does things such as smoke, use his laptop, and talk on the phone about Tom and Jerry...all while driving, crack jokes about eighties movies during autopsies, and of course, he's constantly talking to his imaginary friend Zach, no matter who's around to overhear. Perhaps justified, in that he's trying to protect Zach from the outside world, who doesn't want to form close relationships with people in fear of getting hurt. Acting like a weirdo is a pretty good way to do that.
Nuri from The Chains Of Satinav believes, among other things, that jellyfish can fly, various plants are sapient, and mishandling powerful magic crystals that she has been explicitly told not to touch is a good idea. This might have something to do with being raised in a Fairy Land and having minimal contact with humans.
The museum Curator from Dungeon Maker II: The Hidden War. He's campy as all getout, plus is lacking in basic knowledge and common sense and constantly coming up with ridiculous theories to explain things everyone else already knows. Case in point: at one point he theorizes that snakes shed their skin because they can't use moisturizer cream, so when their skin dries out they just take it off. When he discovers the real reason (snake skin isn't stretchy and snakes will outgrow it) he treats it as if it's a major scientific discovery.
Ignus from Planescape: Torment has a single-track mind and a wisdom score so low that, Statistically Speaking, he is barely considered sentient. He basically lives in his own cloudcukooland and only occasionally comes down to talk to The Nameless One due to a personal connection he shared with one of your prior incarnations. Played for Drama to an extreme degree as he is an Ax-CrazyPyro Maniac and his single-track mind is entirely focused on fire and the potential for everything around him to be ignited. If The Nameless One wasn't around to control him Ignus would default to trying to burn the world down for no other reason than that it isn't currently on fire..
Throughout the Fire Emblem franchise, there's usually at least one character per game whose behavior could be described as eccentric, especially when one considers that most of them are battle-hardened soldiers. Treck from Fire Emblem: Sword of Seals takes it to a new level. Supports with him reveal all the player ever learns about his personality, but it's enough since his behavior includes: ice-fishing while not actually trying to catch anything, falling asleep in the saddle, forgetting other people's names, stating such forgetfulness is a hobby, placidly accepting his and his comrades' deaths, forgetting his own name, interrupting conversations with tangential platitudes and dreading the possibility of turning into a horse...
Setsuna from Fire Emblem Fates is another shining example of this trope. She's generally rather breezy and ditzy, with one of her defining character traits being her Running Gag of falling into traps. When called out on her strange behavior, Setsuna usually manages to somehow interpret everyone's confusion as compliments. There was also the time she managed to cook an apparently-delicious meal by thinking even less than she usually does.
Many characters in the Mario RPGs are somewhat like this, but maybe the biggest case is the Pixls from Super Paper Mario (except Tippi). They don't get much dialogue, but each one has an opening speech when you first meet them that is full of random questions and nonsensical language which has little to do with your quest at hand.
This tips slightly over into Fridge Horror when you realize that they probably got this way because they have been imprisoned in chests for hundreds or thousands of years and have most likely been driven to insanity.
And on into Fridge Logic when one of them asks you whether you like Internet shopping. How would he have known what that was?
Rakesh from Roommates thinks just about anything can be a good excuse for art...or a good place for art...or a good medium or tool for art... There's absolutely nothing wrong with cutting into the kitchen wall to give it some added life, for example, and covering himself with paint in order to redecorate his bedroom is all in a day's work.
Shockwave 2 has a pair of them, both humans who have been stranded on alien worlds for twenty years.
Counselor Bob, formally the UNSF Omaha's science officer, has gone nuts in an alien prison, where he's learned at least five different languages and has to translate everything between groups of inmates. He's very glad to be rescued and turns on you later.
Doctor Yamada, who has had it even worse than Bob by being stranded alone among hostile aliens who would kill him at first sight. When he's discovered, he's been dissecting one every now and then For Science! and has learned how to turn a bone in their reproductive organs into an earpiece for humans that amplifies sound. Despite being less stable at first glance, he is, unlike Bob, just grateful to be rescued and joins the crew.
Tekken: Alisa Bosconovitch shows signs of this, likely because, as a robot, she doesn't have the same grasp of reality her companion Lars has, for example.
Bob Richards is a straighter example, especially in his Scenario Campaign stage - where he will accuse anyone standing with Alisa (whether they are men, women, girls younger than her, bears, or wooden dummies) of kidnapping her, mindless of her protests.
Lili de Rochefort expresses her affection for Asuka Kazama by making up convoluted schemes to get her into a fight. She also usually thinks in terms of what she can have and what she cannot have, people being included in the first category.
Lee Chaolan/Violet shows definite signs of this in the Fight Lab mode in Tekken Tag 2.
In Grisaia no Rakuen Sachi at one point plans an escape attempt that involves blasting through a wall with explosives, sailing a boat through the gap in the wall and then exploding the roof under the prison cell so that their target falls into the boat and then just sailing back out with no fuss. When pointed out that any shockwave big enough to destroy the floor of the cell like that would also kill Yuuji, she amends the plan so that his entire room will be flooded first.
Trevor Phillips of Grand Theft Auto V is this in addition to being Ax-Crazy, which can make for some terrifying situations. He can be found starting fights with body builders because he's convinced they're stuffing their shorts with socks, waking up in the middle of the desert wearing a sundress while surrounded by dead bodies, and riding a motor-scooter down the freeway with another person on a scooter - a complete stranger whom Trevor has decided is his "scooter brother".
The Mario & Luigi series on Nintendo's various handhelds features Fawful, a nonsensical weirdo who on the surface looks and sounds like a goofy bumbling minion, thanks to his swirl-eye glasses, giant grin, and tendency to speak in a combination of terribly mangled English and absurd similies. Go a little further and you'll discover that he's a Dangerously Genre SavvyMad Scientist and The Chessmaster of all things. He exists in his own bizarre little world about 80% of the time, but he's still proven himself to be more terrifingly competent and effective than the better portion of Mario's Rogues Gallery.
Papers, Please has Jorji Costava, a rather inept illegal immigrant who seems to come from a different planet than everyone else; he starts by believing that Artstozka is so awesome that he doesn't need a passport to enter and gets worse from there. He shows up with an obviously forged passport from a fictional country drawn in crayon next, then constantly fails to produce other important entry documents, or show horribly outdated forms of entry. In spite of what should be growing frustration, he's incredibly happy in spite of being turned away or being arrested when you catch him smuggling drugs, which gleefully admits to. While Jorji is a strange individual who doesn't act quite like everyone else, he's very likable, and in several endings he proves to be your salvation.
Papyrus of Undertale is a Hot-Blooded Cloud Cuckoolander, being a self-assured and enthusiastic skeleton who, while helpful and well-meaning, tends to do and say some surreal stuff (even by the standards of this game).
"I WISH I HAD EIGHT LEGS... SO I COULD WEAR 4 PAIRS OF HOT PANTS."