I decided to use dinosaurs as my inspiration since the Kig-Yar aka "Jackals" are actually very dinosaur-like in appearance. These aren't really meant to be specific ranks, but just a few random ideas.
Top Left: Inspired by the Oviraptor. The LED's along the crest were a last minute idea.
Top Right: Pretty much just an updated version of the helmet they sometimes wore in Halo 1. The idea for the eye cover came from the fact that Jackals in Halo 1 had yellow-orange eyes and yet Jackals in Reach had greyish eyes.
Bottom Left: Not really sure what species inspired this one, but I think it was another kind of Oviraptor.
Bottom Right: This one's my personal favorite and was inspired by the Dilophosaurus. That said, the design is actually more based on the Dilophosaurus skull rather than the living creature.
I would've done more, but I accidentally merged the bare head layer to one of the helmet layers and saved it before I realized my mistake.