Glyfair
Explorer
Bran Blackbyrd said:MMII had the Boggle, which I've also always detested, and the Wolf-In-Sheep's-Clothing.
For those who don't know, the Wolf-In-Sheep's-Clothing was a creature that looked like a tree stump with a rabbit sitting on it. The rabbit (actually part of the creature) was just bait, the stump was actually a monster with a gaping maw and eyestalks.
Note that both of these were from modules, originally, and just transplanted to the Monster Manual II. The Wolf-In-Sheep's-Clothing certainly was only intended to be a one-off monster. It was plainly created to make use of the "picture encounter" that was one of the gimmicks of S3.
Boggles, on the other hand, were part of the Slave Lords series and were probably created just to suprise the players with a new monster that wasn't part of the lore, yet. After all, the series was the originally a tournament module.