Grimm - what exactly is a Blutbad?

New show to watch on Hulu!   Grimm - takes Little Red Riding Hood to heart; I like the context.  The vicious blutbad, of which our first amicable encounter is with none other than the "Crazy" from Prison Break, Silas Wier Mitchell.  Oh how I enjoy a family series ....

Silas Wier Mitchell not morphed!


Note:  glad I have the preview mode available - it would have read "Grimm- what exactly is a Butbad?