Aliens. Two-plus meters tall [Revan holds her hand over her head to indicate what she means, though that would be more helpful if she were standing up] furry, strong enough to rip your arms out of their sockets and with a reputation for doing it, too. They're not physically capable of speaking Basic and their language is hard for humans to follow, so that doesn't help. They're really not any more violent than most other species, but when they go off, they're so much better at it that people remember.