(Though in all honestly, if you're here you probably know what a bugbear is. If you don't know, then that paragraph was probably much more detailed than the fleeting wonderment of what a hairy goblinoid brute is.)
I picked the name because it's an esoteric piece of history about one of my favorite D&D monsters. The bugbear is a folklore representation of the boogeyman. In my opinion the name is just as interesting as the creature it's self. As per Wikipedia...
Its name is derived from the Middle English word "bugge" (a frightening thing), or perhaps the old Welsh word bwg (evil spirit orgoblin), or old Scots bogill (goblin), and has cognates in Germanbögge or böggel-mann (goblin), and most probably also English "bogeyman" and American English "bugaboo".
In D&D bugbears are hulking hairy goblinoids (distant cousins of goblins) that are surprisingly stealthy. Their footsteps are silent and prefer to open an engagement with ambush. They break the stereotype of the traditionally stealthy creature, they are not lithe and small. Their shadows fill entire doorways but the weight of their clubs are already cracking and breaking bones before you realize they are there (ask two of my players). I love that they are both brutish and cunning.
"The pumpkin-headed bugbear was an artist taking literally my description of the monster as having a head like a pumpkin, i.e large, flat oval."
I came across this strange illustration just a couple years ago. Wizards of the coast, the current owner of D&D released a limited edition box set of the original little white books that started an industry. I was reading through each of them when I came across a splash page image that depicted a handful of menacing monsters. Right in the middle towering over the others was the pumpkin head bugbear. I thought "What the hell is that thing? It's crazy" The description in the book said very little if anything. Before this, to me bugbears had very different portraits. This one did not look like an abusive mogwai at all. It was child like ingenuity, they took two really awesome things and mashed them together while making laser sounds. Halloween plus bugbears, how could you go wrong? You can't.
Lastly one of the Bugbear gods looks like he'd be down to party.