Which was hilariously spoofed in "The Ember Island Players," with a big muscular guy playing as Toph. While most of the characters overwhelmingly hate their character depictions, Toph, in fact, loves hers.
She's also one of the two most powerful Earthbenders in the world, tied with King Bumi. They once had a fight to determine who was the strongest. They wound up having to stop in the middle because it might have given away their location. But they couldn't hear Sokka telling them to stop, so every other good guy and member of the White Lotus had to stop them. They're later seen planning a rematch.
In Sequel SeriesThe Legend of Korra, Korra displays this trait as well. When the White Lotus Society first meets her, she is already bending three elements with skill...at about age four.
Panini from Chowder. She gives a beating to Gazpacho and Gorgonzola in "The Bruised Bluenana" and "Hey Hey It's Knishmas" respectively. In one instance she threatens Chowder into holding her hand while walking home.
Danielle in Danny Phantom. Being a clone of the main hero gives her all the powers she needs to butt kick.
8-year-old Bobby. Neither a little girl nor quite possessing super strength, but giving the squeaky-voiced little brother of the group a magic caveman club that causes earthquakes on impact has much the same "gotcha" effect.
Jungle Boy from Johnny Bravo, although ironically enough Johnny Bravo is able to injure him quite easily.
Shayera/Hawkgirl in Justice League. While she is an adult, she is easily the tiniest (and most smash-happy) member of the Original Seven. Justice League Unlimited also throws in examples like Supergirl, Stargirl, and Black Canary.
June from KaBlam! can beat you so hard when she's in a bad mood, you might have to go to the ER. It doesn't help that she can lift stuff 5 times her size.
Kim Possible: Pretty teenage girl, cheerleader and scourge of supervillains, for whom kicking henchman ass is a hobby. Also her sidekick Ron's adopted little sister, Hana is a toddler with prophesied "monkey ninja" powers.
Stitch from Lilo & Stitch looks like a blue koala and can single-handedly take down enemies twice his size. It helps that he can lift 3000 times his weight. His preferred weapons are his fists and his jaw.
Don't discount Lilo Pelekai, though. She may be a little human girl, but she's not afraid to get physical as Mertle Edmonds found out the hard way in the first film and Stitch Has a Glitch.
Keoni Jameson(after Lilo throws him out of her house): Wow, she's stronger than she looks.
Jenny "XJ 9" Wakeman from My Life as a Teenage Robot definitely counts. As the theme song puts it, she has "the strength of a million and seventy men".
Applejack, whose jobs are a cowgirl and an apple bucker, i.e. herding large animals and kicking trees. To get an idea of how powerful she is, the episode "Fall Weather Friends" featured a strength contest between her and Rainbow Dash at one point. RD manages to simply hit the bell on the strength-test machine. Applejack? Thanks to years of applebucking practice, she completely destroys it. And Rainbow Dash herself isn't that bad. In the hoof-wrestling part she easily won over Applejack.
Also, seeming fragile flower Rarity, who, when forced into a fight, hardly relies on her magic at all and is far from helpless in combat. This includes straight out punching out a Mook or two at one point. Heck, in the pilot, she kicks a manticore in the face.
In Tom and Jerry cartoons, Jerry the Mouse is usually on the receiving end of pounding and can only get upper hand through cunning and agility. But God help you if you hurt his friend - he will trash you and wipe the floor with your blue furry ass. Moreso with his cousin who doesn't even need the adrenaline surges to pummel cats.
Yin and Yang for Yin Yang Yo! are two cute, technicolor rabbit twins who fare pretty well despite their small statures. Yang who uses might, thus relying more on his strength certainly qualifies although Yin proves more than once she doesn't always need magic to fight.