Orog Invaders:

These beasts have long lived in the underdark and many dwarves can attest to them being ferocious. A sinkhole seems to have opened up which allowed for these larger than usual orcs are dead set on carving a home for themselves on the surface. Some people have said they've seen these brutes bully local goblins into their ranks and that they haul off any unfortunate villagers off to the underdark.