The LEGO Chima series Rhinocerous heads are just screaming to be made into TMNT Rocksteady custom minifigures. So I tracked one down and did exactly that.
I used the cowboy torso from one of the blind bagged series releases, and some random khaki pants. The gun is from a bootleg military minifigure, and I slapped together a sewer lid 'shield' to complete the OG effect.
Rocksteady, Wingnut and Panda Khan minifigures. Now all LEGO needs to do is release a warthog with a mohawk headpiece!