English heavy metal band whose mascot, Eddie, has appeared on almost all of their album and single covers (4,6)
I believe the answer is:
iron maiden
(Other definitions for iron maiden that I've seen before include "used to inflict pain" , "Instrument of torture (a hinged case lined with spikes)" , "Box-shaped instrument of torture - no meridian (anag)" , "a suit, very sharp underneath the surface" , "Group" .)