The reviews for Hansel and Gretel: Witch Hunters haven’t been kind, but one aspect of the movie that does look very impressive is this fantastic animatronic troll head that was made for the movie by Spectral Motion.
You can briefly see it in action in this clip from the film:
Spectral Motion creates some remarkable practical effects. You can see more examples of their stellar work at www.spectralmotion.com.
Special thanks to Steve for originally spotting this!