In the same vein as Batman, Zuko's perpetually frowning, serious demeanor leaves him wide open to many a humorous moment, partially to being paired with his foil of a jolly uncle.note Hilariously parodied in this comic. Subtly acknowledged later in the series when Sokka asks Zuko if he's happy now that he's foiled Sokka's plan, and Zuko replies, deadpan, "I'm never happy." Sokka and Zuko work together in this role almost as well as Zuko and Iroh.
Another female example is the Emotionless Mai, similarly foiled with being accompanied by a cheerful, bubbly Cloudcuckoolander.
Sokka started out as a stern, down-to-earth, warrior-in-training, but his Comically Serious moments, as well as improvisations from his comedian voice actor, soon turned him into a goofy Plucky Comic Relief. Also see him trying to work with a bunch of out-there "nomads" in "The Cave of Two Lovers".
Katara, after having her heart hardened by the events of the Season 2 finale, apparently trades what wittiness she has for more seriousness.
Azula: That's a sharp outfit, Chan! Careful, you could puncture the hull of an Empire-class Fire Nation Battleship, leaving thousands to drown at sea! Chan: ... Azula: Because... it's so sharp!
Korra's airbending teacher Tenzin takes on this role. He doesn't think that the shenanigans going on around him are the least bit funny, which, of course, means he becomes the target of endless inconveniences and humiliations. Also becomes a case of Not So Above It All.
Amon has shown potential to be this, too, if the "Comedy Amon" meme is any indication.
Even in the Grand Finale of Justice League Unlimited, where he threw himself hopelessly at a villain who could take punches from Superman, he was laughing at the Bat's sheer tenaciousness. Of course, in lieu of better ideas, which is what Batman normally does, what else was there to do?
Who can forget the ending of This Little Piggy when Batman is forced to sing? And actually has a great voice!
Zatanna: And you'll keep your part of the bargain? Circe: A deal's a deal. He can stop now. Zatanna:Not on your life!
In "Kid Stuff" when the Justice Leaguers are de-aged into childhood Batman still keeps up his grumpy demeanor. This becomes actually unfunny at the end of the episode, when he reminds the others that he was regressed to the age he was when his childhood came to an abrupt and unhappy end.
A rare Batman laugh came when Harley Quinn told him how The Joker will love her for successfully putting Batman in a Death Trap. However, it was more an Evil Laugh meant to freak Harley out.
In Batman Beyond: Return of the Joker, Terry McGinnis suggests that the difficulty of getting his predecessor to laugh was one reason why the Joker was so obsessed with him, and claims that Bruce Wayne has No Sense of Humor.
Ben 10 (2016) is a Denser and Wackier reboot of the original, meaning that even the villains that are still dangerous have some kind of funny quirk. So when Vilgax (who is virtuallyunchanged from his original characterization) has to deal with the likes of Zambozo or Animo, it's usually comedy gold (until it's not anymore).
Bob's Burgers: Bob Belcher and his emotionless daughter Tina. A major part of Bob's character is that he reacts to the insanity around him the way a Real Life person would.
Daria has just about enough dry humor and witty remarks to qualify as this. Made even more hilarious by the fact that she manages to maintain her dispassionate expression. This is especially evident in the episodes' promos with Jane before the intro of the show.
The central premise behind Droopy was the fact that he never raised his voice, or ever sounded interested in anything. One of the character's Catch Phrases was "You know what? I'm happy." He would say this in the most deadpan, uninterested tone possible. Until you ticked him off sufficiently, but even then the No-Holds-Barred Beatdown was prefaced with "You know what? That makes me mad." in the same deadpan tone as the previous line.
D'jinn from DuckTales (2017) is a perfect example of this. Pretty much every single one of his lines is delivered with a stern expression and dramatic flair, inspiring Dewey to also start making overly dramatic speeches through the episode. He is also fairly gullible in taking everything 100% seriously, to the point that when someone does the "Got your nose!"-trick on him, he actually believes they stole his nose and draws his sword to demand it back.
Bill the Caveman, from the Terrible Thunder-Lizards sections of Eek! The Cat. (The fact that he was also The Chew Toy made it even funnier — "When will the hurting stop?")
Cosgrove from Freakazoid!, taking everything seriously to the point of ridiculous. This is even weaponized, since he has demonstrated the ability to stop any shenanigans by going up to the perpetrator and stoically insisting that they "cut it out", resulting in the funniest possible fizzle on any scene. In the crossover comic with Animaniacs he got the Warners to cut it out.
This is all Adam Westing, since he's known in Real Life for being comically serious (a not wholly undeserved reputation). He's even made jokes about it himself.
The narrator in Goofy cartoons is this without actually appearing on screen—his tone is that of a straightforward educational segment, regardless of the zany antics Goofy is getting into in his attempts to follow the instructions, and it's one of the many reasons they're funny.
Agent Powers and Agent Trigger from the episode "Scary-oke" are a pair of stone-faced MiBs who end up investigating the weird goings-on in town. Powers claims to be physically incapable of experiencing laughter, while Trigger has a tendency to dramatically repeat the last word his partner says, and does things like confiscate an armful of "Mr. Mystery" bobble-heads for "evidence".
Dipper certainly has his moments. Anytime he attempts to look smart and mature, expect it to be ruined by Mabel's or Soos' antics or his own hidden goofiness.
Jellystone!: Huckleberry Hound's tone of voice never goes above a relaxed drawl, even when he flat-out says he feels sad or angry.
Hank Hill, of King of the Hill. In addition to playing the Only Sane Man amongst his bizarre circle of friends, his hyper-mundane personality is often a source of humor in its own right.
Gummy, Pinkie Pie's pet alligator. Whatever insanity goes on around him (which is always considerable when you're the pet of Pinkie Pie), Gummy always wears the same blank expression.
Pinkie Pie's big sister Maud Pie, from the episode of the same name, is funny because she's so outrageously dull and deadpan. This works especially well in her scenes with PinkiePie. Then in "Make New Friends but Keep Discord" she heckles Discord's stand-up routine and draws more laughs than he does, and in "Rock Solid Friendship" she reveals that she also does stand-up comedy with exactly the same deadpan delivery.
Pinky and the Brain — The Brain has a mostly very restrained, stoic and sarcastic demeanor, which, of course, makes it hilarious when nonsensical things happen to him because of Pinky.
Ready Jet Go!: Mitchell. He's a smart and rational kid, but putting him in a silly situation makes for comedy gold. Especially when Jet messes around with him, only giving Mitchell more proof that he's an alien. Mitchell can also be awkward and quirky in a way that's actually amusing.
Benson from Regular Show. He HAS a sense of humor, and he's lightened up over the course of the show, but he can be very uptight, angry, and many of the things listed in the above example. Even when everything going on around him is hilarious, he'll still be red-faced and screaming. "GET BACK TO WORK OR YOU'RE FIRED!!!"
Samurai Jack himself; many of the series' funny moments come from how he usually keeps his serious demeanor despite all the odd situations he's thrown into. Whether polymorphed into a chicken or sporting an eye-popping rave outfit (complete with a pacifier), he still manages to maintain the same determined expression.
Shaggy from the Scooby-Doo movie Scooby-Doo! Legend of the Phantosaur. How could it be Shaggy you say? Well because of his hypnotism. Whenever Shaggy hears the word "bad", he gets so serious it's laughable.
Fred: Shaggy, what are you doing? Shaggy: Saving your butt, Jones! Get used to it!
In Scooby-Doo! Mystery Incorporated, much of the humor comes from Fred being completely oblivious to the silliness of the things he says.
Upon learning that she's been growing magical plants, Glimmer points to a random bunch of them and asks Shadow Weaver what they do. She replies in her usual deadpan tone (midway between contralto and just straight-up chugging snake venom) that "They're daisies. I find them cheerful."
"Brother From Another Series" revealed that this trope is why Sideshow Bob became Krusty the Clown's sidekick instead of his brother Cecil. As Krusty explains after a poor pie-in-the-face gag from Cecil's straightforward goofy clown audition:
Krusty: Free comedy tip, slick: the pie gag's only funny when the sap's got dignity. (sees Bob) Like that guy. Hey, Hal, pie-job for Lord Autumnbottom there!
Bob then gets hit in the side of the head with a pie, causing his huge, bushy, palm-tree-like hair to spring out of his hat and everyone else to die with laughter.
Principal Skinner uses the same tone to talk to his students as he did to command his troops in Vietnam. In the everyday chaos he has to deal with, he'll say the most ridiculous statements (often bordering on Accidental Innuendos) in complete earnest.
Reporter: Principal Skinner, you've been referred to as "the funny one." Is that reputation justified? Skinner:[seriously] Yes. Yes, it is. [crowd laughs]
"The Last Temptation of Krust" had the family visiting a comedy club. Steven Wright walks up to the mike and simply says: "I finally got around to reading the dictionary. Turns out the zebra did it." (Homer is the only person who doesn't laugh.)
Rex Banner from "Homer vs. the Eighteenth Amendment", who's brought in to enforce Prohibition. He's physically unable to laugh, even at his own jokes.
Kent: At the heart of the strike is former student body president Lisa Simpson. Her brother had this to say.
Bart:(chanting) Lisa is a nut. She has a rubber butt. Every time she turns around, it goes putt-putt.
Kent: Indeed, but that rubber butt doesn't have much time for turning around these days; it's pointed squarely in the face of the administration.
Shadow again takes this role in the last first-season episode of Sonic Boom, where he takes the goal of killing Sonic way more seriously than the overly giddy to work with him Dr. Eggman. He also sounds completely serious when he claims Sonic's poor attempt at building a bookcase earlier in the episode is reason enough to justify murdering him.
Shadow: Your shoddy craftsmanship brings shame on all hedgehog-kind. And for that, you shall perish!
The Mask: In "Shrink Rap", Dr Neuman is given the mask by Stanley, who wanted to get rid of it. When Neuman gives in to curiosity and tries on the mask, it turns him into a Psycho Psychologist who goes around accusing random people (including a gorilla) of having "Ipkissia Maskosis" and putting them in atomic wedgie strait jackets. All the while, he mixes his usual deadpan psychologist demeanor with the Mask's crazy cartoony antics.
Craig Tucker, as of Season 12's Pandemic 2-Parter, which solidified his character after several seasons of Characterization Marches On:
Craig: Sir, I promise you, I'm not going to ruin your plans. I'll just walk away. See? [walks onto a square with a pattern on it. The circle in the center of the pattern lights up and begins to rotate up and out. Two stone slabs jut out from the pillar. The golden idol's eyes light up. A beam of light goes from the idol's staff to one of the slabs, and two beams of lightning come out of Craig's eyes] Okay, now there's sparks shooting out of my eyes.
Also the German people, they may have terrible jokes but their completely serious blunt delivery actually make it a bit funny.
Squidward in SpongeBob SquarePants. He does sort of have a sense of humor, although it careers between practical joker and Deadpan Snarker, depending on the situation.
Garnet. Silly things sometimes happen to/around her and she never stops being serious. Case in point, in "Together Breakfast" when fighting a monster made from a demonically-possessed plate of waffles she says, completely seriously, "Now it has all the powers of a breakfast. We have to destroy it!" In "Pool Hopping", she wants to be able to look into unlikely futures, and reasons that to do this, she has to be random and unpredictable. A lot of humor is drawn from Garnet acting ridiculous and being deadly serious about it.
It's revealed in "Keystone Motel" that Garnet got this from Sapphire.
Steven: Uhh, Sapphire? The toilet's frozen. Sapphire: Such is fate. Steven: Am I fated to pee outside in the grass too? Sapphire: Yes.
Peridot, at first. She first assumes that "Steven" is the name of a species that replaced humans, and still thinks the sticker she saw at the Galaxy Warp is an official symbol of some kind. As she starts to lose it from isolation, this trait diminishes, such that by "Friend Ship" she spends the entire episode laughing like a maniac and gleefully tormenting the Crystal Gems. This trait swings around to full prominence in "When It Rains", where she delivers a serious, calculating monologue about trusting Steven after he... explains the water cycle to her.
Lapis has her moments thanks to a lack of social skills. When she first leaves Earth to go back to Homeworld, a dramatic exit is ruined by some awkward pauses:
Lapis Lazuli: Thank you, Steven! Steven: No prob, Bob. Lapis Lazuli:[Beat]It's Lapis... Steven:[beat] ...Yeah. Lapis Lazuli:[beat] Okay, bye.
Yellow Diamond as well, as being called a "clod" by Peridot provokes a hilarious reaction.
As opposed to his originalsource, Shere Khan in TaleSpin is a master of this trope. No matter what insanity is occurring around him, Khan responds to it in the exact same deadpan growl as he uses during a regular business meeting. In fact, if Khan ever smiles at you it's probably a good idea to run like hell.
Gordon the Big Engine in Thomas & Friends. His pompous attitude and desire to maintain his dignity means it's downright hilarious whenever he gets himself into a mishap, whether he bursts his safety valve, has his whistle jammed, or winds up nose-first in a ditch.
Optimus Prime has shades of this in Transformers: Prime. Bulkhead explicitly mentions never seeing Optimus laugh, cry or lose his cool, but funny stuff is made funnier by his completely deadpan reaction to it. After showing a LOLCats-esque internet meme that actually got Ratchet to chuckle, Jack asked Optimus if he wanted to see something funny, Optimus replied rather bluntly "No."
In another incident, Optimus is called upon by Agent Fowler to talk to his superior General Bryce in order to alleviate some tension regarding recent events. Given that Bryce and the camera-man were not expecting Optimus to literally be outside their window, it results in them acting befuddled talking to a 30 foot robot. Optimus meanwhile remains courteous and polite the entire time.
Another giant robot with no sense of humor is the Decepticon Lugnut from Transformers: Animated. Luggy is a gigantic and merciless war machine with a completely serious and fanatical devotion to his lord Megatron. As opposed to his more eccentric partner Blitzwing, he never, ever jokes. He's also often hilarious.
As Transformers: Rescue Bots is in the same continuity as Transformers: Prime, it should be no surprise that this carries over to Optimus Prime's portrayal in that series as well.
Blades: Helping you is... Well, you're bigger than Elvis! Optimus: I have not met this Elvis and am unaware of his size.
VeggieTales: A lot of the humor surrounding the character of Archibald Asparagus centers on his being either the Straight Man to Larry's Wise Guy (mainly in the Silly Songs with Larry segments, which is in fact how the character was introduced — as a parody of the Colonel from Monty Python's Flying Circus, which creator Phil Vischer would pay homage to multiple times more throughout the franchise) or a beleaguered Reasonable Authority Figure (in his second appearance, during the second story on the first video) or Upper-Class Twit (in the Gilligan's Island parody on the second video).
Dr. Clark is a reoccurring doctor character who seems to react to the hijinks of the Bears and others with the same monotone snark.
Jacob Scribble from Wunschpunsch has to deal with the silliest of spells on a daily basis, and reacts to each and every one of them with deadly seriousness.
Chase Young may be dangerous, smart and one evil villain, but he's still a serious character trapped in a rather goofy show like Xiaolin Showdown.
in this role almost as well as Zuko and Iroh.