Grim Grimm guys (5)
I believe the answer is:
ogres
'grim grimm guys' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ogres that I've seen before include "Terrifying types" , "Monstrous giants and man-eaters" , "intimidating people" , "huge figures" , "Man-eating giants of folklore" .)