Solar Auxilia

The badass pre-coursors to the Imperial Guard, they are essentially an entire army of 30k Stormtroopers. When the Emperor finally got over his parental pride and realised that a crusade dedicated to helping humanity should probably have some actual humans in it, he got on with the Imperial Army, drawn from everywhere the Imperium had influence, the elite of whom were the Solar Auxilia. Taking their name from the

"Forge World Wants Your Kidneys"

Recently, as of the fourth Horus Heresy book, the sculptors over at Forge World evidently got tired of multiple flavours of power armour and decided that battles in the Age of Darkness could probably do with a dash of variety.