Danny Phantom: Averted by Jasmine "Jazz" Fenton. She wasn't a spitfire. She was a stuck-up (but caring) know-it-all. But her mother, Maddie, on the other hand...note but she's got brown hair; in fact, most fans think Jazz and her brother are adopted.
Daria: Quinn Morgendorffer, when she gets really worked up. Usually suverted though, since she acts more like a Dumb Blonde, despite having orange red hair.
Mike, Lu & Og averted by Mike. While being a sports loving red haired girl, she is acutally calm and rather laid-back, compared to some shorter-tempered brunette princess named Lu. Though there are a few times when she's pushed over the edge like in "Sultans of Swat" and "To Serve Lu".
Rainbow Dash is a tomboy with tons of attitude, and though her mane has enough colours to fit her name, her bangs are warmer colors (red, orange, and yellow) and are more prominent, while the cooler colors (green, blue, and purple) are mostly hidden behind her neck.
Sunset Shimmer is ambitious, testy, sarcastic, hot-tempered, and red-haired — although admittedly her hair's about an even mix of red and yellow.
Pepper Ann: Pepper Ann Pearson, though she's more spacy and neurotic than fiery. In the uniform episode she admits that it's auburn, which other characters agree to once she tries to take credit for being the trope.
Phineas and Ferb: Candance. However her long hair is more orange than red and is a overactive girl.
Subverted with Gretchen, as she's pretty easygoing, unless you make her really mad. She and raven-haired Spinelli actually swap their normal hair tropes: Gretchen's the brainy one (who was going to have black hair originally), while Spinelli's the fiery one. Played straight with Ashley Q.
As flashbacks show us, Miss Finster was a redhead, and still fiery.
Rocket Power: Mackenzie Benders is an ankle biter with a bitter attitude.
Rocko's Modern Life: Bev Bighead can become this at times, mostly when she's irritated with Ed.
Samurai Jack: The Scotsman is a loud, brutish warrior (and about the closest thing Jack has to a friend). Then there's his wife, who's even louder and more bad tempered than he is.
Kyle is this, often instigated as a result of Cartman's antisemitism, racism, or greed. This can lead to his own Jerkass tendencies, approaching Knight Templar at times. His mother, too, is a full blown fiery Jewish Knight Templar redhead.
Darryl Weathers, leader of an angry band of hicks bent on driving away the job-stealing "Goobacks" who immigrated from the future.
The Adventures of Teddy Ruxpin: Young Hot-Blooded Prince Arin, whom the others often have to restrain from going off half-cocked charging into everything. (Though his red hair is usually hidden underneath a helmet.)
The Backyardigans: Tyrone is usually a pretty mellow Deadpan Snarker, but he's been shown to have quite a temper in some episodes, like "Best Clowns in Town" and "Sinbad Sails Alone".
The Bots Master: Blitzy Zulander is easily the more hot-headed of the Zulander siblings, preferring full-on assaults against the Corp. She's also the main pilot of the combining Humongous Mecha Jungle Fiver.
Averted by calm, rational, redheaded Blossom. The 'fiery' one though is the brunette-haired Buttercup. Although she insists that she IS a fiery redhead in one of the interview promos for The Movie.
Played straight with Princess Morbucks, who throws a tantrum when she doesn't get what she wants.
Headstrong, passionate, and excitable Ray Stantz becomes one in The Real Ghostbusters and its 90s successor Extreme Ghostbusters thanks to an Adaptation Dye-Job (his hair is brown [Dan Aykroyd's natural hair color] in the movies). Ditto the Ghostbusters' Sassy Secretary Janine Melnitz, though to a lesser extent as her hair was already a reddish-brown color in the first movie.
The Smurfs: Sassette was this before Papa Smurf changed her into a real Smurf. That's where she gets her name. Averted in the comic books, where she is more chatty than bratty when she was first created.
Time Squad: Otto is generally outgoing and friendly towards everyone around him, he doesn't appreciate it when adults are mean to him or do something incredibly stupid. Sometimes, the attitude towards these types of people are just plain spiteful. He will often argue and lose his temper all together a few times. Sometimes, he will work out a plan that has the sole purpose of simply humiliating someone, let alone get a mission completed.
Izzy on the Total Drama series. In Revenge of the Island, the normally level-headed Zoey can get this way when provoked.
Cliffjumper is a hotheaded little red Autobot who is extremely paranoid and eager to blindly charge into a fight.
Ironhide is a crusty old veteran, but is also eager to wade into a good fight. Has a red 'helmet' and main body.
Hot Rod is brash, impetuous, and outspoken as a young Autobot, and retains a primarily red/magenta color. Averted later as he becomes solidly brick red as Rodimus Prime, but also becomes more morose, brooding, and jaded.
Warpath is a shouty Boisterous Bruiser with no subtlety and a love of combat, and turns into a maroon tank.
Young Justice: Speedy, aka Red Arrow, was tickedoff at constantly being Green Arrow's sidekick and set off on his own. Despite this, he genuinely cares about his friends and looks after them. In secret.
Steven Universe: Ruby is very much this, having a red tint in her hair along with being red overall. She is veryHot-Blooded, to the point of her evaporating an entire pool because of her anger.
Rainbow Brite: Red Butler has orange hair and a red color motif. He is a headstrong boy.