I'm running a solo D&Desque game right now for a player new to all this weird nerd shit. Because he has no preconceptions of what a number of monsters "should" be, I've taken the opportunity to reflavor some of the classic monster races into versions that I prefer. So Orcs are green-skinned pig-men, Kobolds are rat-badger-dog folk, and Bugbears are actually bear people. And I want to talk about those Bugbears.
Ask anyone who the most hated enemy of the Elves is and everyone, even Elves themselves, will say it's the Orcs. Ask an Elf what enemy they fear the most and they'll hesitantly tell you about Bugbears. When the world was young, Elves were innocent and ignorant of magic, and Humans didn't even exist, the Bugbears were around. If you believe the Elves, Bugbears were a hundred-foot tall Giants who ate whole villages of Elves. It was only with the gift of magic, stolen from the Elvish gods by a reckless warrior, that the Elves vanquished the Bugbears. Unfortunately for the Elves, the victory wasn't a total one.
The rarely-seen Bugbears are 8-foot tall humanoid bears with fur that resembles green moss. Although they have the same general proportions as normal bears, the general structure of their skeletons is optimized for bipedal activity. In fact, much like Humans and Elves, they find going on all fours to be a very awkward experience. A Bugbear's hand is about five inches wide and equally as long; its fingers are about as long as a Humans but twice as thick. Instead of fingernails, Bugbears have two-inch long jet-black claws. These claws are very sharp and Bugbears are very strong; they therefore tend to treat most weapons they acquire as jewelry.
Despite their size and claws, Bugbears are truly dangerous because of two reasons: Their intellect and their almost magical skills of stealth.
Among most adventurers, there's a number of shorthand rules that emerge: "Smaller monsters are more likely to attack in groups"; "Ghost can only be hurt by magic"; and "The bigger a monster is, the dumber it is." That final truism certainly has a bit of anecdotal weight, as shown by Orcs and Ogres. Firm adherents to this saying will dismiss counterexamples of Stone Giants and Dragons as exceptions that prove the rules. There's an idea that the more animalistic a monster is, the more dull-witted it is. Therefore, the inexperienced often dismiss the Bugbear as a dumb brute because of its size and appearance. This is often a fatal mistake. Bugbears are more intelligent than the average Human and are quick improvisers; monster-hunters who think they've got an iron-clad plan for catching a dumb beast are in for a rude awakening.
As for their stealth, Bugbears can even sneak up on an Elf doing guard duty. Despite being 8-foot tall green bear-people, Bugbears make very little sound unless they wish to be heard. Twigs don't snap and footfalls don't echo until they're inches away from their prey. For a Human peasant near Bugbear territory, death can come before they even notice that a Bugbear is right next to them.
Despite this, Bugbears are actually the least destructive of all the Goblinoid races. Yes, they kill and eat peasants, steal food, and often frame other creatures (particularly Elves) but they do this at a much lower frequency than their cousins. Bugbears even form treaties with certain Humans; Bugbears hunt and eat bandits, the bandits' loot is turned over to town authorities, and the town gives Bugbears foodstuffs and miscellaneous goods. Naturally, overzealous adventurers who discover these agreements tend to cause trouble by painting it as some grand conspiracy to undermine the kingdom, so such arrangements are kept secret by both the Bugbears and their allies.
Bugbears aren't very numerous; the average band/tribe is only about a dozen strong, with only about 20% or so of the group being children. Bugbears mature at 5 years of age and can live for up to 100 years. Bugbears have their own language, Bugbearish. Most tribes have a 60% chance to have someone who speaks a dialect of Goblin. Bugbearish has no traditional written form; Bugbears who want to record permanent information do so by phonetically rendering words using Goblin characters. Bugbears have a very respected oral tradition and look favorable on members of other races who share stories with them.
As a counterpoint to the story that Elves tell, Bugbears insist that their ancient forebears were actually trying to practice "tough love" with Elves. They say that Elves were (and are) ignorant animals trying to imitate plants. The Bugbears were trying to show the Elves that they should imitate animals, especially predators. They consider the efforts of the ancestors to have been a failure and that Elves are a lost cause. However Bugbears are usually quite amused to learn about the "hundred-foot tall Giants who ate whole villages of Elves" bit of the old Elf myths.