The below description is taken from LEGO.com.
Boo! Boo who? Boo ME!
The Frightening Knight is very, very scary. No one is quite certain just what makes him so scary. Maybe itís his gravelly, growly voice. Maybe itís his scowling expression, or his intimidating armor and helmet, or his spiky morning star weapon, or the angry-looking bear on his shield. Or maybe he just smells scary somehow.
Being frightening isnít just the Frightening Knightís name Ė itís also his great passion in life. If he doesnít leave everybody who sees him shaking in their boots, then he feels like he hasnít done his job right. All the bad guys agree that heís pretty much the scariest Minifigure around. Even the legendary Fright Knights kicked him out for being just too scary. He could probably be a little less scary if he triedÖbut why would he ever want that?