The Elite Heretics present in Halo 2 that are slain by the Arbiter early in the game. Led by Sesa 'Refumee (Anniversary version is the featured skin above). Not going to lie, I struggled a bit with the base Halo 2 ones, as I didn't want to stray too far from the head shape presented by the other Halo 2 Elites. Therefore, I do think I did better with the Anniversary ones.

All that's left are the TV Show Elites and the Arbiter. I would not hold your breath on a quick release for the latter. I've been holding onto the show skins for a long time now and only have one left, whereas I haven't started on the Arbiter(s) at all and have found myself lacking in motivation. They'll happen, that I can guarantee, just probably not very soon.

Halo 2
Heretic
Heretic Major
Sesa 'Refumee

Halo 2 Anniversary
Heretic
Heretic Major