Here's my favorite guys from the Imperial Guard or Astra Militarum to those who want to be fancy.
The Death Korps of Krieg
These people hail from the deathworld of Krieg, a planet destroyed by nuclear fire. Shamed by the civil war which turned away from the Emperor's light, they vow to dedicate their lives since there is nothing left from the remains of their world.
Using the tactics their ancestors used in the Krieg Civil War. The regiments of the Death Korps specialize in trench warfare, sieges, and attrition battles.

Their zealotry knows no bounds as they charge in droves by the command of their officers, often dying to never concede an inch of ground. This reputation for their ranks has changed the priorities of the commissars attached to their regiments. Rather than shooting those from the Death Korps, they become the voice of reason to prevent additional losses on the battlefields of the galaxy.
One of their most notable operations was the Siege of
Verdun Vraks, a fortress city whose population had became heretics. For eleven years, the Death Korps fought through trenches, craters, and pillboxes in order to defeat their foe and so they did.

Waves of grenadiers charged forth to clear the lines with the transports of guardsmen moving across the fields of no man's land. On the flanks, the infamous Death Riders probe any points of weakness to the enemy's defensive line. Down below, engineers and sappers fight in close quarter battles with shotguns and acid grenades.
Their cold and hard attitude is brought to them by the grim world they live on and they hope to that one day, they die to cleanse the sins of their fathers.
"In life, war. In death, peace. In life, shame. In death, atonement."
- Final litany of the
Litany of Sacrifice, recited by Krieg Korpsmen when entering battle.
Swiftsabre, you are not the only one.