In Everyman HYBRID, Evan is noted as the most technologically dumb of the group and he even seems momentarily confused by the concept of a keycard as a method of opening an electronic lock. He shies away from technology to the point where Vince describes him as an "RL-troll" because he's got a troll mentality (although he's a Jerk with a Heart of Gold at worst) but only checks the Internet once or twice a month. It's considered a big deal when he gets a laptop. He's also a martial artist, he carries a giant bayonet around everywhere, and he even went after Slender Man with a baseball bat.
Captain Hammer has super strength, but fundamental deficits in the intelligence department.
Whateley Universe example: the giant super-strong regenerating monster Killbot (who isn't a 'bot, even if his skin is partly metallic).
Caboose in Red vs. Blue seems to get dumber as time goes on, but he's blessed with seemingly superhuman strength, as evidenced when he effortlessly lifts Andy the Bomb. As Tucker says: "We think it's God's way of compensating."
In Recreation, Sarge comments on Caboose's strength when he effortlessly flips a warthog.
Guts in Berserk Abridged, One of his moments is thinking that menstruation is a myth, along with women stealing men's bodily fluids to create leprechaun. He also thought that the Hawks were literally going to impregnate a castle.
Bogdan, from Water-Human. Speaks mostly in single words, and even is lauded when he manages to compose a sentence for the first time.
Bamm-Bamm from the Global Guardians PBEM Universe. He is perhaps the third (or maybe fourth) strongest person (either hero or villain) in the world, Nigh Invulnerable, devoted to his older brother (the supervillain Eightball), and has Down's Syndrome. A member of Hard Corps, his brother's super-villain team, but only because this lets Eightball keep an eye on him. Want to press Eightball's Berserk Button really, really hard? Make fun of Bamm-Bamm's condition or use any variation of the word "retard" in his presence. Go head. I double-dog dare you.
Carpathia, a government-sponsored Ukrainian superhero from the same setting, is another example. She's nearly ten feet tall, and lift large trucks in one hand, is effectively bulletproof, and is mentally somewhere around eight years old... Her government handlers get her to fight villains by convincing her its all just a fun game, and give her candy afterward as a reward.
In Something Awful's "WTF, D&D" column, occasionally they run an actual Dungeons & Dragons module. In one of them, "Journey to the Rock", Steve "Malak" Sumner played Dean Snakehands, a level 4 elf with stats specifically meant to suggest the barbarian class he wasn't allowed to pick because this was Basic. Raised by frost wolves in the frozen tundra of the north, Dean Snakehands is "a muscley, savage, brutarded elf" with a meager intelligence score of 6. Dean does everything wrong because he's an idiot, but kills giant rock monsters who greatly outnumber him because he's a freaking beast. Despite playing the character for comedy, Malak was applauded for a fairly realistic depiction of an unsupervised slow-witted behemoth.