Ollanius Pius
The most hardcore Guardsman ever to walk the earth and also the legendary saint of the Imperial Guard. Ollanius Pius put himself directly in front a walking god of battle who has just ripped apart a Space Marine Primarch in the hopes of protecting the Emperor of Mankind. The fact that he did so without fainting, shitting himself in terror, or mewling like a wounded grox suggests that his testicles must have been forged from Mars-grade Adamantium. His death proved that Horus had given himself over to chaos completely; and with this in mind, allowed the Emperor to lay down a righteous psychic asskicking strong enough to rend his former son from existence by destroying his very soul. Yeah it was that fucking manly.
Naturally, like so much other awesome shit, Games Workshop has retconned him out of existence (first replacing him with a Spehss mahreen Terminator, and then an Adeptus Custodes) which is SIX KINDS OF LAME. FUCK YOUR CONTINUITY, GW.