Babylon 5: The Legend of the Rangers. "My name is Tirk. I carry heavy things."
Buffy the Vampire Slayer: Glory constantly underestimates her opponents and acts without thinking. The only thing that makes her a threat is that she has a lot of muscle.
Ronon from Stargate Atlantis. Played for Laughs at times and sort of justified because of his past. His "plans" often contain simply Stuff Blowing Up or killing the enemy instead of (necessarily) working together and he's very unwilling to try a more intelligent method. However, he seems to work great with McKay.
"Mission Report: Michael invaded Atlantis. Tried to blow it up. We stopped him. End of report."
Brazilian group Casseta & Planeta had Carlos Maįaranduba, a stupid musclehead with a penchant for violence (parodying the local subculture of the "pitboys") - and anything he deems doubtful of his masculinity leads to a beating. His friend Ulson Montanha is also dumb, though slightly smarter.
Angel: The Beast in Season 4. Just the fact that he has a long-term plan other than mindless slaughter and wanton mass destruction is a sign that he's working for someone else.
This is zigzagged with Gunn, who seemed typecast as the dumb muscle (and he is Genre Savvy enough to be aware of this). That is, through the end of Season 4. The upgrade that Wolfram and Hart gives him is to make him into the brains of the outfit, the Ace Attorney.
Adam, who is the Lab Rat with superstrength, in Lab Rats.