{{Spoiler|source=The Outcast Dead (Novel)}}

The '''Thunder Warriors''' (also known as the '''Thunder Legion'''{{Fn|7}} or '''Legiones Cataegis'''{{Fn|10a}}) were the genetically-engineered warriors of [[Terra]] created by the [[Emperor of Mankind]] to [[Unification Wars|unite the homeworld of humanity]] beneath His rule in the 30th Millennium. They were gene-enhanced warriors created by the Emperor and served as the precursors to the present-day [[Space Marines]]. Wrought to be living weapons, the Thunder Warriors were known to be physically stronger, more savage and more potent in combat than the later Astartes, though they were not as long-lived.