The GRD helmet is an unobtainable helmet seen in the Defiant Map Pack official screenshots. The helmet also made an appearance in the Aniversary Map Pack, in the form of easter eggs.
Tutorial
Following are the GRD doll locations in the aniversary maps. ==Battle Canyon== Go to the area behind blue base identified as "Blue Teleporter" on your HUD and look up. You should be able to see a yellow leg sticking out. Grab the sniper rifle and shoot it untill it falls.