"You could say I'm trying to wake the clods out of their rigid mental sets by forcing them to deal with unconventional behavior... or you could say I just like jerking folks around. For that matter, you could say anything you damned well want to. I do."
Albireo Imma in Mahou Sensei Negima!, who seems to feel it is his job to get a rise out of Evangeline. He's described as her 'natural enemy'.
Zazie Rainyday appears to be following in his footsteps.
Half the time when Koizumi and Kyon from Suzumiya Haruhi talk, Koizumi will explain some theory to explain Haruhi and Kyon will start getting very involved in the conversation and thinking about it deeply—at which point he says "Just kidding, I made the whole thing up." Annoying!
A bad case of this comes from none other than Ryoko Asakura, who decides it's her job to make Haruhi do something and tries to murder Kyon. Actions speak louder than words?
In practice, Kafuka Fuura of Sayonara, Zetsubou-Sensei comes across like this, as while she professes extreme optimism on every subject, she tends to create or encourage chaos by doing so, and we know that she's really Cute and Psycho.
Tsuyuri from Doujin Work is this through and through, causing most of the misunderstandings in the series.
Mai from Nichijou goes to great lengths in order to confuse her friends, going so far as to seemingly confess to Yukko just to provoke a funny response. She'll even troll herself. Also, her dogs are the same way.
And one of said friends has an older sister, who is just as bad.
Shirokuma of Shirokuma Cafe enjoys making things up and messing with his friends because he thinks their lives are too dull.
Manabe from Kotoura-san is a mixture of this and The Tease. He likes having sexual fantasies of his girlfriend and local telepath Haruka so that she flusters, and it's that that turns him on.
Monkey D. Luffy from One Piece does this to the villains, often pointing out their physical features (BIG RED NOSE!!!), seemingly just to make them mad.
L from Death Note does this to gauge reactions from other people, helping him read them more easily.
Yutaka's sister Kaoru from Servant ◊ Service mentioned she likes to play tricks on people when she introduced herself. She's right; the first she appears, she actually staged an Unsettling Gender-Reveal in front of Lucy, making the latter to believe Yutaka is indeed a female for a few seconds!
Amy's "crush" in Sonic the Comic is implied to just be her teasing Sonic because she likes to see him flustered, in contrast to all other continuities where she's a Smitten Preteen Girl.
Bruce: I'm sorry, that was mean. I just wanted to see what you'd do.
Discussed in Plato's Apology of Socrates, where Socrates compares his role for the Athenian democracy as that of a gadfly pestering a horse (for details, see the Real Life folder below).
In Robert A. Heinlein's Rocket Ship Galileo, Dr. Cargraves does this when debating with his three teenage apprentices, to get them to question their own assumptions and realize the importance of being able to prove their assertions. His contrary position is that the Moon might not have a "far side", because no one has ever seen it (the book was written before spacecraft were sent to photograph the far side).
Admiral Chee of Expendable sees himself as a social gadfly in the tradition of Socrates, contantly prodding people to deal with issues they'd rather ignore. Like Socrates, he ends up sentenced to execution because of it.
Byerly Vorrutyer in the Vorkosigan Saga is seen by most people as a gadfly who never saw a foul rumor or vicious innuendo he didn't want to spread. Of course, there's actually a bit more to him than that, and there's a method to his madness, but most see him as an particularly annoying "town clown."
When she can get away with it, Sharleyan of the Safehold series can be this. A specific example involves informing a man of his elevation to a Grand Duke just as the man in question is opening her carriage door for her purely to see the look on his face when the news hits him.
In Midst Toil and Tribulation, Sharleyan is offering generous terms to allow Corisande to enter the Empire of Charis as a member nation instead of a conquered one. She does, however, have one catch she must insist on. She insists that Corisande's princess Irys marry her stepson, who she had spent the book up to that point developing romantic feelings for.
Kavik from Of Fear and Faith likes to push his friends' buttons but it's all in good fun and he's a nice guy at heart who knows where to draw the line. That doesn't mean he won't have as much fun as possible at his friends' expense however.
Live Action TV
Bill McNeil from NewsRadio. At some point, Dave has to explain to Mathew that Bill lies to him "because he thinks it's funny".
In Buffy the Vampire Slayer, Jenny Calendar likes playfully teasing Giles by describing the damage she has either ignorantly or inadvertently done to his books. She's of course well aware of the value of the books and wouldn't think of damaging them: she just likes to see him squirm.
In Elementary Sherlock Holmes' hobby of messing with Conspiracy Theorists may fall under this umbrella more than Trolling, as there isn't any real malice in his habit of playing on their eccentricities for his own amusement.
"My hobby is conspiracy theorists. I adore them. As one would a barmy uncle. Or a pet that canít stop walking into walls.Ē
Satan (yes, that one) from Abrahamic religions. Depending on which text you believe, he might just be Trolling the humans, or out-and-out devilish.
The original use of the term by Socrates was inspired by the story of Bellerophon, who killed the chimera while riding the flying horse Pegasus. A gadfly bit Pegasus, who, startled, threw Bellerophon. He fell to his death, fitting the previous declarations that no man could survive battle with the chimera.
This is essentially the job description of any and all Tricksters in polytheistic pantheons.
Exalted: The Lunars of ages past either slavishly love their Solar mate, or being an extreme gadfly to them. It might have worked as an ad-hoc check and balance mechanism, since the Solars are divinely-empowered god-king superhumans with enough power to rule the entire universe.
Jade Curtiss from Tales of the Abyss. Jade routinely spars with the rest of the party verbally, and no one is entirely sure about his actual intentions. It doesn't help that his Deadpan Snarker nature means that he uses the same tone for nearly everything he says...
Anise: Colonel, what's your secret for being so strong? Jade: Simple. I drink people's blood. Anise: Huh?! Jade: It's so difficult when people take me seriously...
Tenebrae from Tales of Symphonia: Dawn of the New World likes to push his teammates' buttons from time to time, probably the best example being him overhearing Sheena and Regal talking about how close Zelos is to his half-sister Seles, and then deliberately misinterpreting what they're saying as insinuating that he's in love with her. Right in front of him.
Though the other characters like to give him his comeuppance on occasion as well, like when they keep deliberately calling the Nazdrovie a light-frog despite his constant insistence just to annoy him (and then switch back to calling it a Nazdrovie when he gives in and starts calling it a light-frog as well.)
Another candidate would be Malik from Tales of Graces, who does this by telling resident NaÔve Everygirl/Ridiculously Human Robot Sophie ridiculous lies for the lulz. This includes suggesting that Pascal is a rare breed of fish, gills included. He finally meets his match in Graces f when Richard rejoins the party, because Richard is sometimes even better at this than Malik. Especially notable is the skit "Reforming Zavhert", in which Richard leads Asbel, Hubert and Cheria in sweet, sweet revenge:
Cheria: (discussing the dismal uniforms in Zavhert) What if you added a cute lacy frill to the cuffs of the coats? And maybe some designer logos!
Richard: Yes, that might work!
Malik: Your Majesty!?
Richard: And perhaps a sparkling white coat of paint for Fendel tower! I'm certain that would raise spirits!
Hubert: With a giant mech popping out!
Richard: Hahah! Yes, that would be wonderful!
Malik: (distraught) You can't be serious!
Richard:Or am I?
Ange from Tales of Innocence is also a master of this, and like the aforementioned Jade, drops her gems in the same tone as everything else she says, so more often then not the rest of the party believes her until she says she's kidding.
Kamikura Hiroki of Canvas 2 enjoys picking on friends, love interests and students for fun. There are a few he won't mess with, but they are the exception rather than anything approaching the rule.
Zevran in Dragon Age: Origins trolls the other party members in the party dialogue. Or at least, he trolls Wynne and Leliana. He even tells Leliana that he's doing it. Twice. She does get to one up him if she's been hardened, though.
Hawke, the player character, in Dragon Age II can be this when choosing the Witty/Snarky options for dialogue.
Isabela. Trolling is her way of saying she likes you.
Silent Hill 3 has Vincent, who's an asshole whichever way you see him... but a particular exchange he has with Heather in the final dungeon has been a source of debate among fans of the series ever since:
Vincent: Don't stand there looking so smug! You're the worst person in this room! You come here, and... ENJOY spilling their blood! And... and listening to them... cry out! You feel EXCITED when you... step on them and... snuff out their lives! Heather: (uncertainly) Are you... talking about the monsters? Vincent: (giving her an odd look and smiling) Monsters? They looked like monsters to you? Cue horrified reaction from Heather. Vincent: (waving his hands and smirking) Don't worry! It's just a joke!
Gaius from Rune Factory 3 will occasionally drop a line of dialogue hinting that he may be attracted to the (male) player character. It's usually followed by a "just kidding, but your reaction was priceless" sort of justification, but that didn't stop him from being one of the more popular characters in the game.
The protagonist from Devil Survivor 2 can be played this way. Most dialogue options are either serious or silly and some of the sillier ones have him messing with his friends. Think of calling Makoto a pervert even when she finally knocks before entering his room, sniffing her hand when she holds it out to him, yelling 'BOO!' at Io while she's lost in thought or trying to pull Daichi's pants down while he desperately tries to keep a box full of supplies from falling. The way the other characters react shows that he doesn't do this out of malice, but to keep everyone's spirits up in the Crapsack World that Japan has rapidly become.
Karura in Utawarerumono thoroughly enjoys messing with Touka's head. Not that that's very difficult. Also Hakuoro, but she's nice enough to everyone else.
From Touhou we have the flower youkai Yuuka Kazami. In Phantasmagoria of Flower View, there are at least three instances where she lead other characters to believe she's the culprit of the flower incident, or accept their accusations of such. Except that she's not, and was just picking fights for the lulz. She claimed it was just "daily teasing".
Yuuichi in Kanon is fond of making bizarre and outrageous claims while maintaining a completely serious atmosphere in order to confuse all his love interests. Few manage to catch on and also recognize when he is and isn't serious. This works really well considering he's also a Deadpan Snarker.
CLANNAD's Tomoya is practically the personification of this trope. Generally, he's just having fun, but he also has difficulty being honest on occasion. It's most obvious in Tomoyo's route where the only reason he even gets to know her is specifically because he's doing this to Sunohara for shits and giggles.
In Little Busters, however, the resident gadfly isn't protagonist Riki but Kurugaya, who projects an air of a Cool Big Sis and loves doting on her cute classmates, and just as much loves teasing them mercilessly. It's most obvious in the scenes during baseball training, where every day a girl will ask her for advice and she will suggest they do something completely ridiculous and embarrassing. She tells Riki it's for some higher purpose - like teaching them to trust themselves, for instance - but also readily admits that it's mostly just because it's funny.
Lancer can also be very verbally provocative when he wants to be. Extra points for trolling Tohsaka.
Kotomine, as well. He is notable for never telling an actual lie while doing so. Considering he was Rin's guardian after her parents' deaths, she likely learned it from him.
Kenichi in Sharin No Kuni is like this depending on who he's talking to. He more or less leaves Natsumi alone, but Kyouko points out fairly early that he's going to keep messing with Touka as long as she keeps reacting. This trope probably also applies to Isono.
Kenichi also hews closer to the original definition at times - he intentionally disrupts the lifestyles the girls have adopted to work around their "obligations", as well as bringing up uncomfortable topics for discussion, usually relating to some past event in somebody's life he's been clued in to, to help them get over it.
Yuki picks up this role in G-Senjou no Maou though she isn't as blatant about it as Kenichi and it's only really apparent in the Mizuha route. It's never stated outright and is at least partially unintentional since she's simply not good with people, but it's implied that this is frequently what Usami is doing in her sillier moments.
Akira in Suika starts this way, especially in flashbacks. By the end, not so much.
Taichi in Cross Channel adopts this as his default demeanor. He has a hard time knowing where to draw the line and is often far more hurtful than he intends. It's also an act.
Mion Sonozaki in Higurashi: When They Cry towards Keiichi, some of which entails being openly perverted towards said object of her affections. Her twin sister Shion acts this way as well with her teasing but she becomes a horrifying Troll in arcs where she snaps.
Ronove from Umineko: When They Cry is fond of making snarky comments towards his master Beatrice, though she doesn't mind seeing as it makes things less boring. There's also Shannon, who likes making light hearted jabs that most people don't expect due to her usual demure nature.
In Fated Feather, Yote relentlessly teases friend and foe alike (even during moments of high drama), and the beginning of Chapter 7 suggests he does it just because he enjoys getting a rise out of people.
Mike of Shortpacked! is usually a puppy-kicking Jerkass, but occasionally he does or says horrible things to people that force them to acknowledge their own flaws.
Jack Snipe of Erfworld seems to enjoy needling people, and has a particular talent for deconstructing their psychological weaknesses; particularly Wanda.
Black from Grey is... likes to make people angry because he loves the faces they make
In Red vs. Blue, Grif often works as a gadfly to Simmons, most notably when he lies to Sarge about seeing Sheila, just for the sake of making Simmons look crazy.
Ultra Fast Pony depicts Pinkie Pie employing bizarre, long-term pranks just to annoy Twilight. These include pretending to believe she has an unexplainable "Pinkie Sense" and (according to the "Where Are They Now?" Epilogue) learning how to fly.
Andy Kaufman had a separate stage persona for this, and became rather famous for being a jerk due to the difficulty in telling the difference between Andy and Tony. Plus onstage he was already a bit infamous.
Ted L. Nancy, the pseudonymous author of the Letters From a Nut series. Over the course of a few years in the 1990s, Nancy sent a number of hilariously absurd letters to hotels, corporations, and even foreign royalty. A frequent gag involved Nancy writing ahead to make some bizarre accommodation request of a luxury resort. Major news outlets speculated on the identity of this mysterious gadfly, the two most common suspects being Jerry Seinfeld (who wrote the foreword to the books) and Larry David. Nearly a decade later, comedians Bruce Baum and Barry Marder admitted to co-authoring the letters under the shared pseudonym.
Voice actor Phil Hendrie, often called the Andy Kaufman of the airwaves, has a nationally syndicated radio show based entirely on this premise. Hendrie calls into his own show as the "guest", and proceeds to bait callers by taking an outrageous position on some hot-button social or political issue.
I spend my life personally, and my work professionally, keeping the soup boiling. Gadfly is what they call you when you are no longer dangerous; I much prefer troublemaker, malcontent, desperado. I see myself as a combination of Zorro and Jiminy Cricket. My stories go out from here and raise hell. From time to time some denigrator or critic with umbrage will say of my work, "He only wrote that to shock." I smile and nod. Precisely.
The name comes from the term social gadfly. The trope namer, Socrates, said that like a gadfly he could be easily swatted, but that a government who does such thing pays too heavy a price. The gadfly would help improve politics by raising unpopular, controversial viewpoints for discussion. This didn't work out so well for him. Now, the term generally refers to someone who simply pushes people's buttons for amusement.