Subversion: "Try Again" Bragg of Warhammer 40,000: Gaunt's Ghosts. Looks like a Class 2 at first to everyone who meets him, but actually quite intelligent. The plot point of one of the stories in the second novel revolves around Gaunt choosing him for a mission because everyone assumes that he must be dumb because he's big. Also played with in Ezrah, who is very tall but is lanky rather than brutish.
The Ogryn race (OgresIN SPACE) generally fills this role for the Imperial Guard.
Glen Cook's Garrett, P.I. novels have several of these, most notably Waldo "Saucerhead" Tharpe and female Boisterous Bruiser Winger.
Chumley from the Myth Adventures series is a class 3, with a moderate dose of class 5 also. Moreover, as Trolls like him have long found that acting like Dumb Muscle gets them more jobs, his entire race (or at least the male half of it) consists of class 3 Big Guys.
Rachel of Animorphs, despite having more feminine tastes than Cassie, is most definitely this. She has to struggle to avoid becoming a full-on Blood Knight, and still ends up one of the chief dog-shooters and a borderline Token Evil Teammate by the end of it.
It's by preference at first, and later because the team has become so settled into their respective roles that it becomes impossible for Rachel to escape hers, despite her growing discomfort with it. A fact that she blatantly points out (while simultaneously ripping all of our hearts out) in a later book:
Cassie: What are you going to do with him?
Rachel: There's only one thing I can do. I'm going to take him back to the island and abandon him there again. And this time I'm going to make sure that he never comes back.
Cassie: You can't.
Rachel: I have to. You don't have to stay.
Cassie: Rachel, I don't think you'll be able to do this a second time.
Rachel: (Snapping) You know what, Cassie? I don't think so, either. So will you do it for me?
Cassie: (Taken aback) I...
Rachel: (After a long pause) I didn't think so.
Perrin from The Wheel of Time fills this role as a type 2 with occasional 1. He is physically strong since he was a blacksmith, wields an axe and a hammer and is slow-thinking although by no means unintelligent. There's also the Ogier Loial, who fits perfectly into class 2.
Karrin counts when it comes to violence of the non-magical kind, being an expert-shot and Aikido-expert who regularly tosses around cops two or three times her size in her martial arts classes.
Harry Dresden himself is extremely tall (for a human), and among wizards he is considered extremely powerful, if somewhat clumsy in the stuff requiring fine control. Thus he frequently calls himself a "magical thug." Considering his compulsive smart-ass attitude, though, he is definitely a Class 5.
Also by Jim Butcher, Doroga from Codex Alera. His chala is a giant badger, more or less; it goes with the territory. Tavi's uncle Bernard is also a big guy, but not so much The Big Guy.
Porthos, from The Three Musketeers, a rather Hot-Blooded braggart who is only a little less competent than he claims to be. When he's not posing and showing off, anyway.
Jack Reacher is class five, as he uses his brain when he uses his muscles. His brother comes across as a Class Two, but he really can't fight period.
Butler from the Artemis Fowl series. Definitely not dumb muscle, but he certainly qualifies for this trope by taking out a first class LEPrecon team on his own and bringing down a bull troll with not much more than his bare hands. He probably fall somewhere around Class 2 to 3.
French Sci Fi novel Malevil has Peyssou: big, rowdy, lewd, and uneducated.
In Death: David Baxter or Peabody could be placed in this category.
In Septimus Heap, Nicko is type 2, being rather strong from his work at a boatyard but also often carrying the Idiot Ball.
Ham in Mistborn is a Pewterarm, which means he can burn pewter to make himself stronger and increase his endurance. He also happens to enjoy debating philosophy, making him a Class Five. While Vin and Kelsier can also burn pewter, they also have access to all the other metals, while being the big guy is Ham's only power.
Tonk Fah from Warbreaker is this trope, especially in the literal sense. Returned gods also tend to have much bigger builds that also make them stronger.
The Belgariad has a Five-Man Band within the Five-Man Band made up of Big Guys. Barak, an enormous Cherek who turns into a bear and fights with an axe in one hand and a sword in the other is The Hero, Hettar, a fast moving cavalryman acts as his Lancer, archer Lelldorin is the Big Chick, religious fanatic Relg is their Smart Guy, and Knight In Shining Armour Sir Mandorallen of Vo Mandor, who kills lions with his bare hands and threatens armies by himself is Big Squared.
Amanandrala "Grok" Grookonomonslf of the Star Risk, Ltd. series is the Genius Bruiser version. He's an alien with some resemblance to a bear and, in a team full of Badasses, ranks among the deadliest. He's also extremely good with computers and cryptography.
In the Wraith Squadron novels, "unit strongman" is one of the classical roles that Piggy insists keeps coming up, regardless of how the unit changes (he's right). He was one of the originals, along with Runt and Kell (Runt is the best at strongman-type displays, Piggy hits the hardest, but Kell leaves them both in the dust with his martial arts training). In Mercy Kill, Trey Courser also fills this role. Curiously, all four are variations on the rare Type 5 — Kell and Trey are both mechanics, Kell is a demolitionist, Runt was a comms tech, and Piggy is a certifiable genius in math and basically everything else.