Hunters that you can actually kill from the front. They were unassailable from the front in previous Halo installments, but now can be killed from the front as it should be (IMO).

Previous Halo: Shoot a Hunter with a missile launcher, you just made him mad!

Halo 3 ODST: Shoot a Hunter with a missile launcher, you just made him dead!

Grenades can also kill from the front, but don’t bother with the ODST’s frag grenades (which are hard to control) or flame grenades (which just aggravate them). Grenades aren’t necessarily a 1 hit kill, but you don’t have to have a Hunter chasing you around all day until you run out of ammo and finally get killed because melee attacks certainly aren’t the way to go! Grenades plus your weapons can take him out from the front.

I do seem to recall that you could kill a Hunter from the front with a sniper rifle if you shot in the small opening that would be their “neck” (between head & shoulders), but this doesn’t seem to be the case now.

Side note
: Assassin’s Creed 2 is coming!