Shielded dead Elite
From Halopedia, the Halo wiki
In Halo:Combat Evolved,there is a glitch that allows you to see an Elite's shield,when it's dead.
To do this,start any level on any difficulty you prefer, and play through it as normal, until you reach an Elite.Do not attack him, instead, wait until you get behind him, then beat him in the back, so that he'll instantly die.Now that you've done that, shoot his corpse.It should flicker like its shield is not lowered.This works with all types of Elites.It doesn't work in Halo 2.