Freezing Jackal

To see a Freezing Kig-Yar, you must play the Halo 2 level, Outskirts on Legendary until you get to Sniper Alley.

Walkthrough
Get a Sniper rifle or Beam Rifle, then shoot the Kig-Yar that walks into the open in the chest. Usually, he freezes and draws a Plasma Pistol, but very rarely, he dies frozen in midair if you shoot its head. Occasionally, while he is frozen, he will shoot you with the Plasma Pistol.