This one was done a long while back as part of a portfolio of concept art for The Hobbit.
I had this idea for a very distinctive ancestral helmet which would be worn by all the orcish cheiftains in moria, hammered together out of old dwarvish helmets and shaped to look like the face of the balrog, who the orcs of moria worship as a god, and believe that, in taking on his likeness, their chief brings his power onto the battlefield. My thinking was that Azog would come out wearing it at the battle of Azanulbizar, and later when Bolg (who I originally envisioned fulfilling pretty much the exact role that it seems was given to his father in the movie; as this mostly unseen but constant tracking menace) shows up at the battle of five armies, he would don the helmet, which we would recognize.
The spearheads on top are bolg's own addition; the big one in the center is the dwarvish spearpoint that his father's head was impaled on after he was killed in moria, a constant reminder of the blood feud, and over the years others have been added, forming this crest of jutting spikes.
The draped bear hide, displayed with claws and all, is a typical piece of orcish bravado, one which really comes back to bite Bolg in the ass when he meets a certain someone [link]
orc tracker [link]