Marlin from the short-lived 1987 television seriesThe Popcorn Kid definitely qualifies in that trope. An oddball projectionist at a local movie theatre in Kansas City that has seen better days, he constantly lives in a cloudland in and out of his projection booth, quoting and even acting out scenes from classic movies. Occasionally drops some good advice amidst his strange ramblings.
Lisa from Sister Sister. To wit, her idea of "10 Items or Less" has her count every dairy product she buys as a single item, her car has bungee cords for seat-belts, and she keeps Tootsie Rolls in a pillow in case that she or Tia are in a bad mood.
Kel from Kenan & Kel is the bumbling contrast to the more serious Kenan. One episode started with Kel reading the synopsis to an episode of Rugrats instead of their show.
Since the Pretty Guardian Sailor Moon live-action adaptation turns Minako (the anime and manga's Cloudcuckoolander) into The Stoic, Usagi becomes a bit more of a cloudcuckoolander. But the prize really goes to Usagi's mother Ikuko, who seems to live in her own crazy, genki world, complete with wildly different hair styles and colors practically every time she's onscreen, and a fantasy life that, among other things, reimagines her audition as a fitness reporter into a World War 2 battlefield.
Jack Handey, who you can see here, who gave us such "Deep Thoughts" as:
"If you saw two guys named Hambone and Flippy, which one would you think liked dolphins the most? I'd say Flippy, wouldn't you? You'd be wrong, though. It's Hambone."
Tracy Morgan's character Brian Fellow, who interviewed various animal trainers and made inane comments about the animals. Usually at the end, he would have a daydream about the first animal in the sketch that sometimes was completely random (for example, a bunny cutting its hair). And then he reacts to the delusion — in a way that his real second guest can hear!
Will Ferrell's take on legendary Chicago Cubs announcer Harry Caray certainly counts. As the host of an astronomy show, he asks his guests if they would eat the moon if it were made of spare ribs (he would) and proclaims the sun to be his favorite planet, which is why he stares at it. During Ferrell's run on SNL, Caray passed away, but that didn't stop the skits — after a guest asks him about his death, his only response is, "What's your point?" (The real Harry Caray probably fit this trope as well.)
A majority of characters on its Canadian counterpart, SCTV, qualify for this trope, particularly Bob and Doug McKenzie. The brothers would talk about random things (usually involving beer) and bicker with each other over something else.
Mayor Tommy Shanks is corrupt because of this trope. There were also a few occasions where he feeds his stuffed animals dog treats.
Dimwitted newsman Earl Camembert, among other things, tried to eat his dinner at the news desk once, and in an attempt to seem youthful and in-touch with what the youth wanted in a journalist, roller skated onto the news set to disco music and promptly fell flat on his face. (Extra hilarious because the sketch in question aired in late 1980- in less than a year disco and roller skating to it would be completely out of fashion.)
Dewey is the archetypal Cloudcuckoolander, and attracts others of his kind without trying. (Wide-eyed, silent Egg: cute enough—in his extremely dorky way—to avoid Creepy Child status.) It's revealed in one episode that whatever Mom is really saying in earshot of him, he just hears "Dewey Dewey Dewey...".
Hal. It Runs in the Family. For example, when he and Craig Feldspar are obsessed with an arcade dance competition, Lois reminds him that can pursue this as far as he wants as long as he follows the rules he has agreed on with her in the past, such as that he has to continue to remain employed and she gets to freeze their joint checking account for the duration of his obsession.
Cosmo Kramer of Seinfeld. Although, his problem isn't that he doesn't understand what's going on around him, or what is or isn't considered acceptable by society, but rather that he doesn't care, and thus behaves as if he were oblivious.
Dougal McGuire has to keep a list of things that don't exist, including "non-Catholic gods", "the Phantom of the Opera", and "Darth Vader". In the very first episode, he had a diagram explaining the difference between dreams and reality, and still got confused.
Mrs. Doyle is one as well, as is Father Jack Hackett, being both a senile old man and an alcoholic. "The Plague" gives us this gem while in "Hell" we have this.
Hank from Corner Gas. He often daydreams about various oddities, sometimes confusing other characters. In one episode, he not only wonders who would win if robots fought werewolves, but also mentions how impressed Vikings would be if they could travel through time and see all the glow in the dark stuff we have. He spouts sexy, poetic language while on fishing trips, causing other characters to be attracted to him regardless of their sexual orientation. One episode of the series takes place almost exclusively in Hank's mind because someone told him to think before he spoke.
Richie and Eddie from Bottom start off in this situation and descend occasionally into ditz territory. When they think they've killed a gas meter reader, Richie suggests they eat the corpse in order to dispose of it; when they go camping, Eddie lights the Sterno without inserting the valve and almost sets himself on fire; and then there's the following exchange over a crossword puzzle:
Richie: Hey, I'll tell you what... Why don't we think of another word that means "ironmonger" but only has six letters? Eddie: Heh! Well, that'd be cheating, wouldn't it? Richie: Who's to know? Eddie: Hah! You're right, me old pal! We get through a few scrapes, don't we? Richie: Yeah, so, where are we? Eddie: Er, right. "Ironmonger", six letters.... Oh, got it! "Harold." Richie: Harold? Eddie: Yeah, well, he's an ironmonger, isn't he? Harold the Ironmonger, remember? We ate his dog! Richie: Oh right! Yeah, we bloody won that bet, didn't we? Eddie: ... Uh, no, we didn't. That's why we had to eat his dog.
J.D., when faced with problems outside medicine, keeps coming up with solutions involving monkeys, gnomes, or his head being independent of his body. Sometimes his statements sound more bizarre to the other characters than they are, because they didn't hear the Inner Monologue leading up to it, but more often, knowing what he was thinking just makes it weirder.
Todd's Inner Monologue: Oh, great. There he goes off into his fantasy world. Now I'm stuck waiting until he snaps out of it with some weird comment.
Molly: So, where were we? J.D.: Uhh, we weren't talking. Molly: Was it cause of something you did? Cause I'm totally over it, I don't even remember what it was. J.D.: No, I mean like, we've never talked. Ever. Molly: Well how do I know your name then? J.D.: You don't. Molly: (playfully) You're freakin' me out, Jimmy!
Phoebe Buffay is probably the most well-known example for a mass-media audience. For instance, she doesn't believe in evolution or gravity, and was convinced that her deceased mother's spirit returned in a cat.
Rachel's sister Amy. She's not able to remember her niece's name (she keeps calling her Ella instead of Emma) and thinks "Phoebe" is just a weird noise, not able to realize Phoebe is telling her her name. She keeps confusing Ross with a guy who sells fast-food. She also starts a business as fashion advisor and designer for babies and is surprised that parents don't like hearing that their babies are ugly.
While quite sane in the first few seasons, Joey ends up fitting this trope in later seasons. His intelligence seemed to drop off and he was very particular about food, not sharing it with anybody and eating quite excessively.
Jack Gellar can be something of one as well.
Mad About You has Ursula, the waitress at their usual restaurant, who is played by the same actress who plays Phoebe from Friends. (The characters are twin sisters.) The food must be really good. Also Ursula showed up on Friends a couple of times, and Phoebe was the smart one.
Dwight Schrute is someone who, while his behavior is mostly predictable, seems to have motivations and an internal monologue that indicate that he is one of these.
Creed is a kleptomaniac, doesn't understand the concept of a blog and was judged by Ryan to be too dangerous to own one, is unaware of how uncomfortable he can make people, rarely ever does work, but still has a job, and managed to trick Michael into convincing him to keep it.
Erin who grew up in various orphanages and hospitals before getting her receptionist job. For example, she throws away disposable cameras after using up the film roll lamenting that she will never get to see the pictures she took.
Major Gowen in Fawlty Towers typically understood about one-third of any conversation that didn't involve the game of cricket. His cognitive skills usually failed at a critical juncture of one of Basil's schemes. He once went to a remembrance service, but didn't remember it.
Trudy from Reno 911! tells a story of how she mistook a goat for a Turk (or maybe vice versa), and seems to think that she's in a relationship with the openly gay Lt. Dangle.
Chip:(regarding being a superhero) I mean, no one's more excited than me to finally get to wear a cape. Xander: "Finally"? If I remember correctly, you used to come to school with a pillowcase pinned to your back. Chip: Yeah. But that was a long time ago. Xander: That was last week, mate.
Trip of Power Rangers Time Force and Ziggy, Gem, and Gemna from RPM. Ziggy's the Only Sane Man among the Ranger Series Operators, even calling out the others for passing judgment on Rangers Gold and Silver's zords. ("Look in the mirror, people: We're in no position to be sitting in judgment of anything weird!") Gem and Gemma are adult children who, like Dr. K, have been raised in a government think tank codenamed "Alphabet Soup". And, since very little backstory is given for the duo, no one really knows just how they got their personality quirks.
Dustin from Ninja Storm and RJ from Jungle Fury. Dustin's a maybe, while RJ might just be one of the best examples we've got.
River Tam. While she is actually insane, she does have lucid periods during which she is still endearingly unpredictable. Notable examples include her deciding to imitate Badger's accent while deconstructing his gangster facade and her attempt to "fix" Shepherd Book's Bible. It's difficult to tell how many of these moments are due to Cloudcuckoolander-ness and how many are actually because she's kind of a genius. Then there's the time she asked Shepherd Book to marry her to her brother and then stuffed a pillow under her shirt to claim she was pregnant.
Racer:Summer Glau! Wow, you were the best part of Chronicles. Summer Glau: I eat my body weight in food every 31 days. That's slightly faster than the human average. Nathan Fillon: ... Yeah, there's a reason she only plays strange roles. Summer Glau: I'm part of the floor now.
There's Jubal Early, who goes off on random tangents for little or no reason, though it is implied that he does it to keep his "audience" off-balance. It might also come from him being a psychopath. At the very least, he has this exchange:
Simon: So you're a bounty hunter. Early: No, that ain't it at all. Simon: Then what are you? Early: I'm a bounty hunter.
While not excluding the possibility of insanity, he may also be hard of hearing, given his confusion when Simon asks "Are you Alliance?" and he heard it as "Are you a lion?".
Cliff Clavin of Cheers occasionally drifts into this territory. Coach and his penpal (they traded pens) Woody also qualify
Frasier: Hello in there, Cliff. Tell me, what color is the sky in your world?
Norm: Okay, Cliff. At what point in your life did you come to the fork in the road, where sanity was to the left and you took a hard right?
Margaret in One Foot in the Grave sometimes lapses into this despite usually being the Straight Man (er, woman). Every now and then she will make some wild claim that makes very little sense, sometimes seeming a bit out of character. For example, when talking about friends who have died to her husband Victor, she mentions someone who apparently died of a terminal disease:
Victor: What, measles? Margaret: Well she died, didn't she? Victor: ... She fell off a cliff! Margaret: Only because she went to the seaside to convalesce!
Cat of Red Dwarf. He seems to have entirely different morality than humans.
Cat: I hate to get all technical on you, but: all hands on deck! Swirly thing alert!
Mork. Granted, he's an alien, but the reason he was sent to Earth in the first place was because he was considered weird even by Orkan standards. (And, judging by the other Orkans we meet in the series, especially Orson, they're right.)
Exidor. The man with a different religion every time you see him.
Wendy's neighbor Noser from The Middle Man seems to do little else but sit in the hallway with a guitar and quote lyrics and pop culture references to Wendy.
Cassie. "Oh, it's cool. I wear a white dress and now I can eat yogurt, cup of soup, and hazelnuts now. I'm not sick if they let me play with the cats. Yeah, it's like... hazy days, y'know?" In the series 2 episode "Jal", she uses this sort of thing as a way of trying to help Jal make a decision regarding whether or not to tell Chris about her pregnancy or to abort it. So, she may be using it as a ruse sometimes as well.
Topanga from Boy Meets World started off this way, but eventually the role was taken over by Eric, who made anything Topanga did look sane and rational by comparison. Will Friedel is a natural comedian and very good at improv. A good deal of his lines in the later seasons were the result of Throw It In, particularly his singing of "Ooh, Child" to Trina McGee and this:
Eric: I'm gonna miss you... You were always my favorite.
Eric: ...I dunno. (walks away)
Bubbles from Trailer Park Boys, who lives in a shed with his many cats. Bubbles may actually seem retarded because of his awkward gait and absentmindedness, but he actually seems to be one of the smartest people on the show.
He actually borders on Ambiguously Autistic; he's legitimately bright, but his brain is... not like our brains.
Walter Bishop from Fringe is still a brilliant scientist, but spending more than a decade in a mental institution has given him a few quirks like obsessing over certain foods and constantly forgetting the existence or just the name of one particular member of the team. During the 1970s and '80s, he regularly tested the psychological and neurological effects of LSD on himself as well as doing it recreationally might have contributed. Also having a chunk of his brain removed by William Bell at his own request probably contributed too.
Lowell on Wings sometimes takes extra-long strides to avoid "Cosmic Potholes," for fear he'll be lost in time.
French Stewart's Harry Solomon in 3rd Rock from the Sun; actually, when he was repeating the voices in his head (from the Big Giant Head, q.v.) he sounded much more reasonable than he usually did, albeit officious and megacorporate.
The entire Solomon family count to some degree, due to being Starfish Aliens in human bodies with little understanding of human culture (or even human biological functions.)
Cameron from The Sarah Connor Chronicles has an odd tendency to go off on random spiels and discussions without any warning, including one instance where she starts measuring the exact center of the house to determine when it will need to be repainted in a couple of decades, or when she randomly goes off quoting Bible passages. In her case, its actually quite justified, as her processor is damaged and thus renders her slightly unpredictable.
Spending years in prison for a crime he didn't commit seems to have made Detective Crews from Life slightly unhinged. He says things that make his partner ask if it's a "Zen thing", has an odd fruit fixation, and has a decidedly offbeat manner in dealing with the public.
Jane: I once went on holiday and pretended to be twins. It was amazing fun. I invented this mad, glamorous sister and went around really annoying everybody. And d'you know, I could get away with anything when I was my crazy twin Jane. Sally: But you're Jane. Jane: Kinda stuck. It's a long story.
Most of the characters on the original The Electric Company, perhaps with the exception of J. Arthur Crank. Fargo North, Decoder counts as both a Cloudcuckoolander and a Genius Ditz.
Lewis: Well, I just want to say one thing. "Earl" minus L is ear. How much more clear could it be? Drew: Lewis, "clear" minus "cl" is ear. Lewis: No, now you're reaching.
Oswald shares Lewis' disease.
Oswald:(about Kate) I did carry her 8th grade picture around with me in my wallet. I told everybody she was my girlfriend. It was kinda sweet back then, but now I get the weirdest looks.
"Howling Mad" Murdock from The A-Team. Each new chapter comes with a new personality/distorted reality. Still he's a remarkable pilot and as skilled as the other members in most areas. It's also implied that some or most of his insanity is an act, as he considers the mental hospital his 'room and board' and would prefer to stay there.
Wesley: She's either counting oxygen molecules or analyzing the Petri dish she just put into her mouth. Or sleeping. I can never quite tell.
Fred also resided in Cloudcuckooland for a while; the small room she occupied in The Hyperion, for example, was covered with random thoughts she had in magic marker. She was only this way because of her mental trauma from being a slave in the demon dimension, Pylea. She recovered gradually, and became a useful asset to Angel Investigations.
Then there's Drusilla:
Drusilla: I'm naming all the stars...
Spike: You can't see the stars, luv, that's the ceiling. Also it's day.
Drusilla:I can see them, but I've given them all the same name, and there's terrible confusion.
Also subverted with Drusilla. She's incredibly dangerous, but at least some of her persona is Obfuscating Insanity.
Andrew is also one to an extent.
The Buffybot is obsessed with Spike, chipper about slaying and much friendlier than the real Buffy, if socially awkward.
Zora from Sonny With A Chance. In the pilot episode, she actually thought Sonny's presence meant she wasn't the weird one anymore. It didn't work out that way.
The Doctor of Doctor Who is an example of a Cloud Cuckoo Lander that managed to be pretty damn good at what he does, but nevertheless retained his disdain for mundane things like reason and reality, even in his more serious regenerations (One and Seven in particular), with regenerations like Four and Eleven constantly breaking the Cloud Cuckoo Lander scale. A lot of it is Obfuscating Stupidity to fool his enemies, but most is because he just operates on a different level than everyone else. This could be justified by being a Time Lord, a civilisation that had been making the fabric of time and space their bitch for millions of years before the Doctor was born, except numerous episodes demonstrate that even other Time Lords find him weird.
The Big Finish Doctor Who audio drama Caerdroia has the Eighth Doctor develop a literal split personality, and his Cloud Cuckoolander side (substantial enough to begin with) gets its own body. The most normal personality says he "doesn't even seem to be living in the real world", and therefore attempts to deny usually being the same person as he is.
The Doctor's various companions are well aware of his... eccentricities, and have to repeatedly justify not only why others should listen to the Doctor, but also convince themselves why, exactly, they put so much faith into this crazy person, for example the episode "Flesh and Stone":
Bishop: Doctor Song, do you trust this man? River Song: I absolutely trust him. Bishop: He's not some kind of madman, is he? (beat) River Song: I absolutely trust him.
The episode "The Doctor's Wife" demonstrates that the TARDIS is even more of a Cloud Cuckoo Lander than the Doctor, with a heavy dose of The Cloudcuckoolander Was Right. Having your mind spread across all of time and space will do that to you.
The one-shot companion Layla from the Tenth Doctor audio story "Dead Air" doesn't bat an eyelash over the fact that the Doctor is an alien or the idea that her boat has been invaded by a being made of sound that eats noises, instead being mostly concerned with finding out if they have kettles and trouser presses in space.
Many characters on The Young Ones have a touch of this, but the top candidates for Cloudcuckoolander on the show would be some of the Balowskis, particularly Reggie ("Hello, Mr. Pussycat! What you doing in a bucket?") and Brian ("...a helicopter, £100,000, a complete set of steak knives, some of those little black rubber things...").
Stiles Stilinski from Teen Wolf is a Teen Genius who suffers from ADHD, constantly goes off onto Motor Mouth tangents, and spends most of his time as the only human in a group of werewolves. That last issue has only exacerbated his already bizarre habits.
Coach Finstock: For his final question for his mid-term exam, he detailed the entire history of the male circumcision.
Sheriff Stilinski: Well...I mean...it does have...historical significance, right? I mean...
Tyler from My Hero, one of the few characters who know about George Sunday's alter ego, Thermoman. This isn't the crazy part; the crazy part...what is the crazy part? The tea parties with Frodo Baggins seems the most likely candidate.
Parker from Leverage. Described by one of her teammates as "twenty pounds of crazy in a five pound bag." She has very little social skills and often makes inappropriate yet accurate comments. However, she is very skilled in other areas such as improvisation when it comes to thieving. Word of God says that Parker has Asperger's Syndrome. It's a pretty accurate depiction.
From British sitcom Miranda, while best friend Stevie is more of a Bunny-Ears Lawyer, Miranda definitely counts. She spend more time messing around in the joke shop than actually working ("How about a game of Biscuit Blizzard?"), has an alarming tendency to burst into song randomly and has no concept of the fourth wall. It's deconstructed in the Season 3 opener, when Stevie actually quits the shop because she's fed up of Miranda never taking anything seriously. When Miranda later gets a normal office job, her Cloudcuckoolander nature just doesn't fit and she quits fairly sharpish, the pair soon reuniting when they realize just how boring life is without a Cloudcuckoolander to share it with.
Her mother also has traces of what I call "Cloudcuckoolander tendencies".
In Farscape, John Crichton was originally this to all the aliens in the far sector of the galaxy where he was stranded, because he was constantly riffing off references to popular Earth culture that an 18-35 y/o American male from the late nineties/early 2000's would have been familiar with. Due to various psychological traumas experienced over the course of the series, including having a virtual doppleganger of the Big Bad in his head slowly driving him insane, over the course of 4 years Crichton becomes a Cloudcuckoolander to everyone.
Stark is another good example from Farscape. Driven to the brink of insanity by a lifetime of slavery, torture, and having to absorb the souls of the dead, Stark tends to drift between mad obsessive gibbering and long, disjointed anecdotes... and that's when he's at his calmest.
Dave from Titus. Once got so high he remembered being born.
The Muppet Show has Gonzo the Great. Well, what did you expect from a guy named Gonzo? When you're the weird one on that cast, that's saying something.
Mason from Dead Like Me. At various points has believed that college is a plot by bacteria, there's a giant dust cloud in China stripping the flesh off cows, money from parking meters goes through underground tunnels, and if you drilled a hole in your head it would increase the amount of blood in your brain and get you really high. (He died of that last one, and after forty years he still seems to be unaware that was a really stupid thing to do.) He also once tried to lick a lit match. Most of it is because he's almost always on something, and when he's really, really high, he gets even weirder:
"I've got a leak in my bottom!"
Brittany from Glee started out as a nameless background dancer, but has evolved into this. While many of the characters (Emma, Finn, Quinn) can be a bit spacey, it's hard to imagine Brittany as a functioning person in real life.
I'm pretty sure my cat's been reading my diary.
Did you know dolphins are just gay sharks?
I've been here since first period. I took all of my antibiotics at once and now I can't remember how to leave.
Sam Evans from Glee is also an example of this, though to a lesser extent as opposed to Brittany. Quite often he is right about what he is saying, as he is actually very attuned into 'people' and somewhat wise, but usually expresses his thoughts using some sideways story or crazy impression to get there so often times people do not realize until later what he meant.
Mr. Eldridge from Remember WENN. He also has a tendency to take things literally. But on occasion, he can be very wise, as when he helps Gloria Redmond get over her husband's death.
While there are few characters in The Mighty Boosh who don't meet the full Cuckoolander criteria, The Moon probably tops them all - and he's so popular with fans that he has his own Web site. And yes (for those unfamiliar with the series), the Moon, as in the actual celestial object, is a recurring character within the show. He typically appears a couple of times per episode, grinning down benignly from the heavens and treating us to some staggeringly random asides and anecdotes in a curious Eastern European accent. His comments never bear much, if any, relation to the plot (then again, the Boosh is a Big Lipped Alligator Show if ever there was one) although the other characters do seem able to interact with him on occasion. Tony Harrison once stopped and asked him for directions, only to be greeted by a completely uninvited rant about telescopes. Tony was forced to deem him an "alabaster retard" and move on.
The Moon: "You know people say if you look at the moon for too long you can go mad. I think that's quite true, coz you know Patrick Moore? Well he's been looking at me for years and years, and yesterday I saw him do a shit on a salad."
Vince Noir also fits this trope, like this for example:
"What's your favorite animal?" "Probably a panda, because they're cute and cuddly but at the same time they can be fierce, like GET OFF MY BAMBOO!!!"
Mr. Bean is the golden standard by which all other cloudcuckoolanders are judged. Perfectly underlined by the Mr. Bean opening sequence where he seems to fall down from the clouds (or space?) into the spotlight provided by a streetlamp.
"When I was younger, I actually thought I was an angel because I had a round face. And I thought about becoming a nun — Sound Of Music — but I really like boys, so I didn't. Not all boys, there's one boy. More man. Man-boy. He's totally... *unclassifiable wibbling noise*"
Hiro Nakamura from Heroes has this, always in reference to geek lore that occasionally confuses people around him if they don't know what he's referencing. However, in the 4th season when his mind was screwed with, he ends up speaking in NOTHING but geek references to talk about something else entirely, and seemed to think that he was Don Quixote. His friend actually took him to a comic book shop so he could translate what Hiro was talking about. Eventually he figured it out.
Charlie Kelly from It's Always Sunny in Philadelphia. His favorite food is milksteak. With jellybeans. Although he more commonly eats cat food, and would very much like to eat whatever it is hornets make. And he thinks the sound of cats walking around is too loud and needs to be quieted with mittens.
Barney from How I Met Your Mother at times seems to be a more grounded version of one of these. He's perfectly capable of functioning in the world, but occasionally displays a brand of logic that wouldn't make sense to anyone else but him. For example, when he, Robin and Lily are trying to sneak into a high school prom, one of his plans involves asking Robin how capable she is with a crossbow. There's also this exchange in 'The Possimpible' when Barney is trying to make Robin a video resume:
Robin: (dressed in a karate outfit) Barney, I can't break fifteen bricks with my forehead! Barney: Robin, it's not the 1950's anymore. Yes, you can.
Raj from The Big Bang Theory can be like this sometimes. Sheldon, on the other hand, can be considered this a lot of the time, just with a Genius Bonus. Leonard's and Howard's utterances in the episode "The Adhesive Duck Deficiency" are just as Cloudcuckoolandish and they were all making them past each other simultaneously. Well, they were all high on 'special recipe' chocolate chip cookies when this conversation took place:
Raj: If I could speak the language of rabbits, they would be amazed and I would be their king. Leonard: I hate my name. It has "nerd" in it. Leo-nerd. Howard: I lost my virginity to my cousin Jeannie. Raj: I would be kind to my rabbit subjects... at first. Leonard: You know what's a good name? Angelo. It has "angel" and "jello" in it. Howard: It was my uncle's funeral. Our eyes met across the table over the pickled herring. We couldn't help ourselves! Raj: One day, I hold a great ball for the President of France, but the rabbits don't come. I'm embarrassed so I eat all the lettuce in the world... and make the rabbits watch. Leonard: People would call me Angie. Yo, Angie! How you doin'? Howard: To this day, I can't look at pickled herring without being a little aroused and ashamed.
Nick from My Family isn't quite right in the head.
Nick: I don't want you to loan me 200 pounds. Ben: Good. Nick: Don't you not wanna know what I don't want it for? Ben: Yes, I do not. Nick: I'm not gonna start the world's first drive-through Santa's Grotto. Ben: Good, because that's a really bad idea. Nick: I'm glad you like it. Ben: Why are you telling me about this if you're not going to do this? Nick: Reverse Psychology. Ben: It's not working. Nick: Ooh goody, can I have the cheque now?
From the same show: Roger names his dental tools after Lord of the Rings characters, and Abi is... Abi, and that's really all there is to it.
While Robert Goren from Law & Order: Criminal Intent mostly uses this trope as a form of Obfuscating Stupidity to mess with suspects, he displays plenty of these moments without any justification to qualify, especially considering his mother has been confined in an asylum for the past 20 years. (He visits her every week; nobody is sure if, any given week, he will come back.)
Zach Nichols has his Cloudcuckoolander moments - more than Goren, even - with Nichols lampshading this in an episode when talking to his partner, explaining that being the child of psychiatrists can drive one crazy at times (especially since psychiatrists who burn out are said to potentially go just as insane as some of the individuals they deal with on a regular basis).
Castiel of Supernatural may count, as he has a terrible time understanding human culture, including (among other things) taking the voice on his cell phone way too seriously:
Twin Peaks. Agent Cooper. And about half the cast, really, but Cooper is king of the hill. His mentor at the FBI, Gordon Cole (played by director David Lynch, something of a cloudcuckoolander in real life too), was clearly an influence.
Agent Cooper: "Harry, I have no idea where this will lead us, but I have a definite feeling it will be a place both wonderful and strange."
Gordon Cole: "COOPER, YOU REMIND ME TODAY OF A SMALL MEXICAN CHI-WOW-WOW."
His was-to-be-girlfriend Audrey is this, too. She is an unusual example, being sultry, attractive and quirky at the same time.
The Mayor in Spin City comes through in the occasional crisis and was much more normal in Season 1, but he's clearly not very bright or rational much of the time.
Codie on Step by Step is highly eccentric and lives in a van. By many accounts he's dumb, but he also happened to outscore Dana on the SATs and often becomes the voice of reason in family crises.
The title character of Merlin probably comes across this way to the other characters at times (the scene where he tells Gwen he's checking her house for giant rats, stealing Arthur's food 'to keep him in shape', accusing apparently innocent people of being trolls and demons), but his actions all make perfect sense to the audience.
The fact that he often turns out to be right probably keeps him from being written off as a total lunatic, though his bizarre behavior does seem to keep people from treating his claims seriously, at least initially.
Gaius Baltar from Battlestar Galactica (Reimagined). If you pretend you're one of the thousands of people with the sole exception of Caprica Six who can't see the Six that he's always conversing with, he comes off as more than a little bit not all there.
The Hybrids. They're constantly spouting what seems to be gibberish, but can often be interpreted as speaking prophecies. It's mentioned that one theory is that because they live their lives as the minds of starships traversing the galaxy, they simply have a clearer view of the universe. Another theory is that they have seen the face of God, and it has driven them mad.
JB from The Elephant Princess told Alex that Marcus would like jewelry for a present, after being told off by Amanda for suggesting that Marcus should buy Alex a videogame.
Adam Savage of Mythbusters is made of this, used as a deliberate contrast to Jaime, who is The Comically Serious. Tory is the Build Team's Adam, though Grant is close competition.
Every character in the main cast of The Addams Family exemplifies this trope. They are consistently portrayed as out of step with the day to day norms of society, yet they believe they are the normal ones and everyone else is odd. Due to the macabre nature of their idiosyncrasies, most of the other cast members on the show (particularly the Normanmeyers from the second animated incarnation) consider the Addams to be Nightmare Fuel Station Attendants, but because the audience is in on the joke and invited to see things from the Addams' point of view, the horrified reaction of the other characters becomes a bigger joke than how out of step the Addams themselves are.
This is cited by most characters as evidence that he is the sanest person in the unit, as he's the only one who is actually using any means to get the fuck out of there before he's killed or driven insane, instead of playing along and waiting to be discharged.
Brick from the Spiritual Successor of Malcolm in the Middle, The Middle, who even looks like Dewey, loves books to the point where he treats librarians as some sort of celebrity, has an unusual knowledge of fonts, and tends to repeat things after saying them. These are some of the more normal things he does. normal...
Faith Fairfield on Hope And Faith occasionally lapses into this trope (when Hope went off to college and joined a sorority, Faith thought she had joined a Greek cult for four years) though she's usually The Ditz(and she's also a Dumb Blonde to boot).
Joey from Full House. He's a grown man who watches cartoons. That by itself wouldn't mean much. The fact that he constantly talks to people using cartoon voices for no apparent reason does.
You could usually pass Moss in The IT Crowd off as just very eccentric, but he can't quite seem to grasp that not everyone is a computer expert/fanatic, and don't force him to make up a lie unless you want a very big one...
Picket Fences had a rather dark Reality Ensues take on this. The character involved, who would often spout amusing nonsequiturs in the middle of dramatic murder investigations and was one of the funnier guys on the show, turned out to have Alzheimer's, which led to a tragic downward spiral.
Top Gear's James May usually comes across as fairly sensible, but during the news segments he tends to go off on random tangents or draw strange conclusions that leave his co-presenters wildly confused or squicked.
Such as his Insane Troll Logic that because people slow down to avoid hitting deer in the countryside, but for some reason, tend to speed up in cities and end up causing road accidents;
Zone: Yeah? Topher also thinks he's a little teapot short and stout. Adelle:Topher Brinks is a genius! And you will keep a civil tongue in this house or we'll put your tongue in a stew.
Most of the supporting characters from Dick & Dom in da Bungalow are daft, but attached to the real world. The Prize Idiot is from somewhere else entirely, where swimming trunks and flippers and a little plastic hat are the perfect attire for hanging out on a Saturday morning. Obsessed with cheese sandwiches.
"If Eddie were one of the Beatles, I think he'd be George. I don't know why."
Mr. K from Go On. Occasionally hilariously creepy to boot.
"I like your teeth. Can I have one?"
In the Everybody Loves Raymond episode "Peter On The Couch", Robert lampshaded the fact that Peter was very much this trope. He tells Amy that Peter "is a little *starts shaking his head and making funny noises*." Amy then admits that she and her family have always been aware of this, replying "I know. We ALL know!" She then notes that "You know, your family is a little *makes the same motion and sound* too."
Jeff. You could practically write an entire page just with examples of the bizarre things he says or does over the course of the series. He does get better once Awesome makes him stop sleeping in his van, though.
Chuck himself is this as far as the spy world is concerned. It's not just his inexperience, either. Even after Intersect 2.0 allows him to become a full-fledged spy Chuck has his share of these moments. Not many spies consider internet porn or a box of fruit juice to be acceptable tools for disarming nuclear bombs.
Alexei Volkoff may have actually squeezed more crazy into one season than Jeff managed over the entire series as a Large Ham arms dealer who seems to spend half his time living in an entirely different reality. His personal, heavily-armed yacht has a fully-stocked ice cream parlor. He calls it his "Floating Fortress of Fun."
Constable George Crabtree is the resident Agent Mulder who always suspects that ghosts, werewolves, vampires, Martians or Venusians killed the victim of their crimes. Sometimes he starts talking reasonably enough with common sense and intuitive brilliance, but it ends up as downright crazy. He admires Murdoch's inventions or experiments, and suggests some interesting uses for it. One time he wants to employ microwave energy in the kitchen. When he's told that such a device would have to be huge, he dreams that one day, perhaps every hotel and every restaurant might have a potato-cooking room.
Constable Henry Higgins is more grounded than his friend and colleague George, but he sometimes eagerly follows and extends his wild theories.
Derby from Mr. Young. In "Mr. Time", his hand gets tired from holding up a piece of paper on a window. Adam tells him to just use tape, so he tapes his hand to the paper. In "Mr. Heart", he gets involved in a "Fantastic Voyage" Plot, and is afraid to swim through the blood stream. Not because it's blood, but because he's afraid there might be sharks in it.
Mrs. Howell from Gilligan's Island is often off on another planet, concerned about social niceties and proper attire in the weirdest circumstances.
Mrs. Howell: Whatever does one wear to deliver a ransom?