Jimmy is the franchise's adorable boy genius. This was especially evident in the shorts, movie and season one where he was a lot more shy, clumsy, awkward and naive. This is why he gets a lot of attention from girls both in-universe and in fandom.
Brittany Tenelli. She's ditzy, off-the-wall and as sweet as a jellybean. She's also the funniest one of the group, although she usually doesn't mean to be. Brittany is also easily confused because she's often lost in her own little bubble. More of her adorable moments include her giggling and trying to flirt with Nick.
Cindy often acts shy and sweet around Jimmy when she's trying to flirt with him. She also acted like this towards Nick in the movie and early episodes.
Jimmy's two best friends, Carl and Sheen. They are both just as geeky as Jimmy, through neither of them is nearly as bright as him. Carl is a Lovable Coward who is obsessed with llamas while Sheen is a Keet who is obsessed with the comic book Ultra Lord.
Zuko's adorable face + hilarious failed attempts at being social = this trope. Zuko's adorkableness started in season 2 in "Ba Sing Se", particularly his date in Tales of Ba Sing Se. Exhibit A.◊ His Fan Nicknames are "Zudork", "Dorko", and "Failko", and that encapsulates his attempts at being normal. Poor guy reallyCannot Tell a Joke. It's rather funny and odd because he spends most of the time being a no-nonsense warrior, Wise Prince and stern pursuer. But when he's forced to be social, he fails hilariously.
Zuko:(after months of trying to capture or kill Aang, wishing to now join the group and teach Aang firebending) Hello, Zuko here. But I guess you probably already know me, sort of. Uh, so, the thing is I have a lot of Firebending experience and I'm considered to be pretty good at it. Well you've seen me... you know when I was attacking you? Uh, yeah, I guess I should apologize for that, but anyway I'm good now. I mean, I thought I was good before but now I realize I was bad, but anyway... I think it's time I joined your group and taught the Avatar Firebending...
Zuko is like this even when he shows up in The Legend of Korra at age 88. When he goes with Korras dad and cousins to check on combustion bender PLi in her prison, he tells them that he hired someone with a similar power to kill Aang once. All Tonraq can do is give a WTF? expression, probably processing the fact that he just said he tried to get someone to kill his best friend. Zukos response is , Didnt work.
Zuko's sister Azula fits as well when she's not outright terrifying for it. In fact, when it comes to normal interactions, she's worse than he is. At least Zuko gets the idea of how to read audiences and tries (even when failing) to communicate normally. Azula has absolutely no idea how to talk to the opposite sex, or how to play sports without treating it as a battlefield.
The Earth King who is extremely naive for his age since he was kept in the palace his entire life while Evil Chancellor Long Feng took care of politics. He is sometimes even called "King Adorkable." Seriously, his pet bear is much more worldly and mature than he is.
Meng from "The Fortune Teller" is a female example. A young girl with pigtails that defy gravity and a missing front tooth, who believes Aang is her destined lover solely because of his big ears.
The professor/archaologist Professor Zei from "The Library." Loves his work with a passion, fanboys over Aang not because he's the Avatar but because he is a "living fossil," tries to communicate with Appa (while hushing Momo), admires Won Shi Tong's "foxy assistants" (actual foxes) for being handsome and clever, and can not understand what is so funny about the term "flying buttresses" because he's too busy being genuinely enthusiastic about architecture. He's also almost a Perpetual Smiler in a non-creepy way. Yeah, he lives in his own little world. Although this fascination with Won Shi Tong's library ends up getting him killed.
Most of the science types are your classic hot badass types... then you have Hank Pym, who will geekily squee about the science-influenced powers of a guy trying to kill him.
On the female side of things, there's Wasp, who also happens to be Hank's not-girlfriend. Seriously, she's d'awwww-worthy in most of her scenes.
Batman: The Animated Series had quite a few. Most of the rogues can fall into this category at some point in their portrayal, and characters like Alfred have their moments. The series is simply full of it. Harley Quinn is probably most notable for being painfully adorkable when she tries to interact with the public after her release from Arkham (short lived), but also good examples are the Ventriloquist, when he's simply being Arnold, and Jervis Tetch, when he's either at war with himself, or prior to his spiral into madness. Tetch in particular, had some incredibly adorable moments of complete social ineptitude in his office; talking to people, especially pretty people was not his forte.
The Brak Show has Brak, who is a naive and somewhat gullible cat-like alien creature who constantly breaks out into an impromptu song. His "friend", Zorak, takes advantage of his naivety for his own amusement at times.
Quite a few characters in Camp Lazlo are this: including Slinkman, Raj, Clam, Edward, Samson, Chip and Skip and Lazlo. Dave also has shades of this.
Penny Sanchez with her glasses, studious personality, and an utterly adorable voice courtesy of Hyden Walch. Helps that she is only ten years old, making her even more adorkable.
Rudy Tabootie is also pretty adorkable. He's a little shy and awkward, an absolute sweetheart, and acts dorky around his crushes (such as Penny and Trina from "The Crush"). The fact that he has buckteeth and big ears just add to his dorky cuteness.
Lola from Charlie and Lola. She's eccentric, clumsy, and at times rather annoying - but you just gotta love her.
Jérémie from Code Lyoko. He's got a 99.87 grade average and ungodly computer programming skills, and has worked tirelessly for two years to give Aelita a normal, stable life. So that makes him a colossal nerd, an angel of a love interest, and just downright adorable physically.
In his comfort zone as The Leader of Sector V, Numbuh One is a calm, collected badass. Outside of his comfort zone—i.e. during father-son bonding, or in romantic situations—he is a total nerd.
Numbuh 3 for her cute, ditzy personality. She also acts like a little girl, and is Asian and Nerdy as well.
Danny Phantom, especially in his human form. Sweet, awkward, shy, clumsy, those wide baby blue eyes, and more. His phantom form in the earlier episodes could count, being nervous and scared when he started out.
Even Wilhelmina has her moments. Particularly when her more giddy and girly side is shown.
Doug: Doug Funnie is a shy, clumsy, awkward young boy with an enormous heart, which makes him adorable.
DuckTales (1987): Launchpad McQuack is somewhat awkward and accident-prone, and also boundlessly enthusiastic and good-natured. He's a favorite with a lot of people, in and out of universe.
DuckTales (2017): Webby. She's learned all sorts of adventuring skills from her Granny, and spent most of her life researching Scrooge and the McDuck family. But she's socially isolated and therefore (adorably) awkward around peers (like the nephews or Lena). Also adorable when she geeks out over a new piece of McDuck lore. (Huey and Dewey have also been described this way, and Della might qualify as well; time will tell.)
Ed. He's a lovable oaf with a silly, playful and innocent personality, and has a number of odd obsessions including sci-fi movies and comic books.
Edd. Everything about him is adorkable. He's cute, geeky, neurotic, endearingly shy, kind, polite, and quite a Shrinking Violet, especially around girls. And that's why all the girls (In-Universe and out) find him adorable.
Eddy can come off as this at times, especially when he gets tongue tied over Nazz.
Jimmy being a cute, delicate, accident-prone kid who cries easily and has a lot of Woobie moments.
Jonny, a weird but good-natured Cloudcuckoolander. He's especially adorkable when he's interacting with his Companion Cube Plank, a piece of wood who is also his best friend.
Timmy Turner himself is a cute little boy who loves comic books and video games. He also isn't very popular at school and is shown to be quite witty from time to time. His big tooth also helps.
Cosmo (particularly in early seasons) is a goofy and ditzy guy who nonetheless loves his godson and wife... he just has a weird way of showing it.
Tootie, Timmy's Stalker with a Crush manages to be this - she wears huge Nerd Glasses, has braces and absolutely loves Timmy. Also, despite the fact that she tends to be annoying and creepy (not to mention that Vicky, Timmy's evil babysitter, is her older sister), she is mostly just a friendly, cheerful girl.
Meg Griffin because she looks like a geek (she wears glasses), she's called a "wannabee loser", and because of her Butt-Monkey status she's constantly picked on and made fun of. You can't help finding her downright Adorkable.
A parody of Hugh Grant, poking fun on his many roles and typecasting: "I'm just so charmingly befuddled."
Phillip J. Fry, mostly due to his childish nature and his kooky mannerisms, and he's a Trekkie. He's not seen as particularly attractive in-universe, but he manages to date some fairly hot women at times.
Kif Kroker, Zapp's meeker, smarter alien assistant, who tends to be a nervous Extreme Doormat and becomes painfully shy when he's around his love interest, Amy.
Dipper is an "awkward and sweaty" pre-teen who is absolutely horrible at interacting with people (to the point where he has to make a list when wanting to speak to his crush) - however, this makes him a very endearing character, along with the fact that he'll do just about anything to impress people and make his twin sister happy.
Pacifica Northwest. She's had such a controlled upbringing, so governed by others, her parents especially, that she really has no idea what to make of social situations on her own and appears to be naive to things as basic as sharing. Because of this, not only does she get along very well with Dipper, but it can be downright entertaining to see him trying to look cool in front of her.
Pacifica: "Wait, leaving already? You're at the world's best party, dummy."
Dipper: "I'd love to stay, but I've got a category ten ghost to depose of." *walks right into a pillar, but makes a quick recovery* "Ehehe. Category ten."
Billy is a goofy Ditz who (by his own admission) loves everything (except clowns). It's sometimes offset by his many Gross Up Close Ups, and it's definitely more evident in earlier episodes; nevertheless, he's especially lovable when eagerly getting along with Mandy and Grim.
The eponymous character. He's a such meek, friendly Nice Guy and a very sweet child who gets along with nearly everyone. It's hard not to find him cute when you combine that with his huggable appearance.
Claire is a shy and nerdy little girl who loves anime and has a huge crush on Foo, often drawing her and Foo together in an anime style.
Piri Piri an extremely sweet and idealistic daydreamer who loves to make art. She's also an immense Cloud Cuckoolander (she says her art is inspired by her dreams) and is revealed to have feelings for Harvey in "Secret Gordon". Even her voice is adorable!
Harvey probably gets his adorkable nature from his dad Irving, who is shy, sensitive, and a bit of a klutz, but also a very kind and loving father and husband.
Tenzin, which is especially funny because he spends most of his appearances being super serious and pretending to not have a sense of humor. And then Korra brings up his romantic past with Lin Beifong. Tenzin's Not So Stoic/The Comically Serious moments are largely what contribute to his Adorkable status. A lot of his facial expressions during his Not So Stoic moments wouldn't exactly look out of place on his dad.
Lilo & Stitch: The Series has Lilo. She's such a friendly, sweet-natured, but socially awkward girl who has a strange obsession with Elvis and taking photos of fat people, and loves hanging out with her best friend, Stitch, an alien from outer space.
Milo Murphy himself. Unlucky beyond reason, but always optimistic and upbeat about it. Always seen wearing a sweater vest. Unfailingly kind and polite to just about everyone. Totally geeks out upon seeing an antique firetruck.
Vinnie Dakota. A fully grown man who gets just as excited about going to the zoo or trick-or-treating as a kid. Also clearly cares a lot about his time-travel partner and would do anything for him.
Jenny whenever she deals with the real human world. Her appearance is quite cute and her insecurities and innocence can be quite endearing.
Sheldon. Not only is he a geeky Gadgeteer Genius, but he takes no effort into fitting with society due to his awkwardness. He has quite a crush on Jenny, who he is often helpful and sweet to when he gets the chance. It's really hard not to like him.
Twilight Sparkle is essentially a former shut-in who's just learning how to maintain friendships. Despite this she can still spend days cooped up in her home reading books, and has evinced a tendency toward Super OCD that borders on the scary. It's on full display when we see her dancing skills (or lack thereof) at her birthday party in Canterlot, and she takes it Up to Eleven when she was a filly, in "The Cutie Mark Chronicles". In "Castle Mane-ia", she lays eyes on the library in the castle. She can now squee in three dimensions.
Seems to run in the family: Twilight's brother Shining Armor was a huge nerd before becoming a guard. When he gets a chance to talk to his crush Cadance for the first time, he manages to croak out a very awkward "Hello"; Cadance's observation is "Could he be any more adorable?"
Rainbow Dash, Passionate Sports Girl and Lovable Jock, can be adorkable, particularly when she's fangirling over The Wonderbolts and Daring Do, an Indiana Jones Expy. She's even willing to wear a very dorky looking sweater while posing with an owl. She also has some really cute moments with Fluttershy like going to see the Butterfly Migration just because Fluttershy asked. She can even be adorkable when she's not fangirling in episodes like Flight to the Finish. Like this◊.
Rainbow Dash: Aww... get to the nitty-gritty later! Tell 'em the important stuff! Like, who's the coach?! *blows whistle* That's right, ME!
In addition to being the regular kind of adorable, Fluttershy also has her share of adorkable traits as well. Normally she's very well... shy, but if something piques her interest, such as animals, she'll get excited and starts talking your ear off.
Even Rarity at times. She prides herself on gems and fashion and possesses vast knowledge about both (in the former's case, her cutie mark is three diamonds). She even wears glasses sometimes while making dresses.
Nightmare Ned: Ned Needlemeyer is a nerdy, bespectacled 10-year-old who is shown to be quite nervous and timid, but also demonstrates a kind-hearted and endearing personality.
Oggy and the Cockroaches: Oggy. Besides being an expy of Tom, he often keeps trying, and failing to capture the roaches, and he is the biggest Buttmonkey of the show.
Kowalski from The Penguins of Madagascar. He is a nerdy and highly intelligent penguin who is obsessed with science and reacts with almost child-like glee whenever something sparks his interest. He also has an unrequited crush on a dolphin named Doris.
Candace is that rare big sister example, due to her neurotic Butt-Monkey-ness. She also Squee a lot, tries to get her brothers in trouble, and fails miserably.
Doofenshmirtz. There's practically no shortage of cute nerdiness in this show! He has a miserable childhood, his adulthood is not much better, and it's possible if he is a misunderstood individual or not.
Bubbles. Her playful, naive, and childish attitude as well as the love for stuffed animals qualify her for this. She is the sweetest of the girls, and would never want to do anything bad for a person in need. It helps that she's probably the youngest of the trio.
The Professor. He would cause accidents, and is clumsy, but is also sweet, and there are times where he can really care for his children.
Blossom. She is intelligent and looks absolutely cute. In her spare time she likes reading.
Gina, a Cute Mute like her older sister. She doesnt get much characterization, but her short stature and the way she always has her hand out makes her downright adorable to see.
Even Nubia has her moments. Particularly in the episodes, The Party, where she has a fan-girl moment when meeting Lou Rawls and at the end of It Takes a Theif where she blushes after Wizard Kelly, Jr calls her Snookums.
The title character tries to be cool, but he's such a goof that he comes off as charmingly quirky.
Julian. He's the perkiest of goths, to the point where it could put Ruby Gloom to shame; he's eccentric and an aspiring magician; he has Cute Little Fangs; and he has a soft, sort of creepy yet adorably shy voice (courtesy of Dee Bradley Baker). All of this bundled into a very cute, friendly, likable character.
Even Mitchell can be this when he's not being a Jerkass, especially in the episode "Solar-System Bake Off!", where he acts socially awkward around Jet and his friends when he is trying to gather information about their entry, especially Mindy.
Mikey's naivety mixed with his Large Ham tendencies make him adorably dorky.
The Pale Kids are a group of nerdy ten year olds who spend their recesses playing Daggers & Dragons and reading comic books.
Miss Grotke has many cute, dorky moments throughout the series. It's her over-enthusiasm about everything that really hits it.
T.J. can be pretty adorkable. His ditzy Book Dumb moments, his overly enthusiastic and optimistic nature, and he's got an enormous heart. And he was a Shrinking Violet in kindergarten! And he's been revealed to be a huge geek when it comes to comics.
Gus is a shy cutie who doubles as The Woobie. He's a timid, naive, insecure yet good natured boy.
Chuckie Finster, a nervous, awkward kid with a heart of gold.
Chuckie apparently inherits from his dad, Chaz, who is equally neurotic and good-natured.
Stu Pickles, an inventor who is bumbling. He also can be childish at times, such as in "A Tale Of Two Puppies", when he begs Didi to get a puppy.
Sabrina: The Animated Series: Harvey. Unlike the live-action sitcom where he was a popular jock, here Harvey is a cute but nerdy weirdo who has girls fighting over him anyway, including Alpha Bitch Gem.
Adora manages to be played as both an Amazonian Beauty and as this, especially in the early stages when she's still very much a Fish out of Water. For example, her first ever party has her reduced to Stunned Silence by her first encounter with a horse.
Adora: (having accidentally ripped her overly comfortable mattress) Glimmer! Glimmer! I think I killed the bed!
Glimmer herself is very enthusiastic and upbeat, at least early on, which can lead her here given that she's still a bit of an awkward teen. She gets a lot more serious later, as The Chains of Commanding start being piled on.
Bow has an endearing earnestness to him as The Heart, and is also a huge nerd for First One tech. He's the guy who came up with the title "Best Friends Squad".
Scorpia is good-hearted, scatterbrained, and surprisingly socially awkward when not hitting people for the Horde.
Entrapta is an even bigger socially awkward nerd, to the point where she treats a party as a social experiment, but her upbeat, friendly and determined outlook earned her a lot of fans out of universe, and even managed to touch the softer side of Hordak.
Hordak himself is a cold, menacing Darth Vader Clone...but when he tries to actually express sincere thanks to Entrapta it's possibly the most awkwardly endearing thing he's done in any version of the canon.
Lisa Simpson, as smart as she is, is still a little girl, so she does have her moments of adorable dorkiness. She really loves her Malibu Stacy doll and on her Christmas list, she listed "pony" over and over again.
Milhouse has Nerd Glasses and is a naive, socially awkward boy who suffers some of the worst luck out of all charaters. Not to mention about his crush on Lisa Simpson.
Homer Simpson at times, at least when not being a complete jerk. He's awkward, not that smart, but his goofiness and love for Marge make him lovable. Also, just look at him when he was a child.
Ralph is an oblivious and innocent kid with a huge imagination who tends to make weird and inappropriate comments all the time. Despite his frequently stupid and odd behaviour, his father adores him.
Waylon Smithers is an older guy, but he counts due to his adorable vibe, his Nerd Glasses, and his traits of a perfect way of completing Mr. Burns.
The title character from Skippy: Adventures in Bushtown shows shades of this, but Pos the cameraman possum probably fits the trope even better. In the Title Sequence, Pos is shown trying to film Skippy walking towards him but the he trips walking backwards and falls on his butt so Skippy doesn't bump into him. It's only 1 or 2 seconds long and yet it is completely adorable.
Spongebob. An endlessly cheerful, optimistic and kindhearted sea sponge with Innocent Blue Eyes.
His cousin, Stanley S. SquarePants, is a self-conscious Klutz who geeks out at the chance to take photos with some of the Krusty Krab's customers while working as a cashier, and is voiced by Christopher Guest to boot.
Spongebob's loyal friend Patrick is a chubby, lovable but not very bright pink starfish who's just as childish and carefree as Spongebob, if not more.
Rusty from Squidbillies due to his naive nature. Rusty is the only character who has any sense of consequences or morality and is easily the nicest character on the show.
Steven is an enthusiastic, dorky kid who is awkward about introducing himself to Connie, gets really worked up about things like birthdays or breakfasts, and will adopt as his new best friend and/or beloved child virtually anything that sits still long enough, even acid-spewing bug monsters or fully-grown lions.
Connie is very shy and self-doubting, but after meeting Steven, she shows a much more vibrant and energetic side around him. She discusses her favorite books with glee and shows an absolutely adorable eagerness to join Steven in his adventures.
Despite being a villain, Peridot gets in on this quite a bit, with her overall immaturity, high-pitched voice, and tendency to squeak when startled. After Steven lightly taunts her in a confrontation, complete with Eyelid Pull Taunt, she can be seen mimicking both the taunt and his preceding smug expression later in that episode. Doesn't help that in most of her appearances, she's not that big of a threat. Cranked up in "Catch and Release", when it turns out that without her limb enhancers she's no larger than Steven and even nerdier than anyone had ever suspected, pulling off stunts like slap-fighting with Steven and attempting unsuccessfully to flush herself down the toilet to escape◊...and then again in "Log Date 7 15 2", where she explores life on Earth by getting obsessed with a Canadian teen drama, donning Goofy Print Underwear, learning how to tell jokes, and gloating over how impressed everyone will be by the paint-can stilts Steven gave her.
While not all iterations count, Donatello tends to fall into this category, particularly the 2003 show's version. Soft spoken and gentle, noticeably awkward and even clumsy compared to his brothers, and that's not even getting into the Teen Genius bit. Considering that the turtles don't have irises most of the time, the amount of emotion he conveys through his eyes alone is incredible, and can make big-hearted viewers want to hug him.
The 2012 show has Leonardo take the steed. While still the leader of the group, he also has a fondness for an old Sci-fi show and uses this as his basis of being a leader. And it is adorable. It's approaching ridiculous moe levels combined with his big blue eyes and the expressions he makes.
While this term is used to describe Ho Yay between Noah/Cody, the Paris episode proves that Noah on his own certainly counts.
Beth has many traits of adorkability, especially how awkward she acts when she interacts with the other characters.
Pahkitew Island brings us Max, the aspiring supervillain whose attempts at being evil always backfire. He's later revealed to have a soft spot for kids, and states that he never spent his life being social.
The same season brings us Dave, a hypochondriac who often freaks out when he gets remotely dirty and has a tendency to get himself in awkward situations, such as accidentally kissing a bat on the lips, climbing out a confessional toilet, and accidentally telling Sky he's glad she was stung by bees instead of him (believing he's allergic to bee stings).
Panda who is emotional, worried about not getting a girlfriend and not as social a his brothers and he's also an Otaku.
Chloe Park who is intelligent, cute, socially awkward with humans but gets along well with the Bears.
Winx Club: Tecna acts like a robot a lot and it's suspected she didn't have any friends or feel emotions before meeting the rest of the Club, as well as her boyfriend, Timmy. No bowtie, but still adorkable, as the pairing is.
Tim Drake as the new Robin in season 2 has his moments, especially when he gets nervous and flustered when put in charge of leading team alpha and his facial expressions to his teammates' antics.
Captain Marvel is this almost from his first appearance, where he clearly just wants to hang out with the Team and be their friend, trying to do everything he can to be nice, friendly and helpful to them. However, since the kids are generally mistrustful of the League (as some of their mentors have been keeping secrets from them), they wind up keeping him at arms length until they find out that he's just a 10 year old kid whose superpowered form happens to look like a 30 something year adult.
Zatanna is this in season 1, mostly stemming from how she reciprocates Dick Grayson's banter and occasionally uses Buffy Speak in her spells.