I recently had a thought: what do you think the theme music for the factions, and factions within the factions, of 40K could be like?

This all started when I listened to these songs and thought an Orchestral version could be a decent theme song for the Grey Knights:

This one actually starts with Church bells, and might be a better fit for a different Imperium faction:

the Sabaton song might be a better fit for the Adeptus Custodes

Admittedly, some of the lyrics would have to changed to make them fit for the 40K setting.

What are some other songs that would fit different factions of 40K?