The Crux Terminatus is a stone medallion awarded to highly skilled and experienced Space Marine Veterans. All members of a Chapter trained in the use of Terminator Armour will have been first awarded the Crux Terminatus. These badges, set into the left shoulder plate of Terminator armour, are highly distinctive and usually fashioned from stone. In Codex Chapters, members of the Chapter's veteran First Company are the exclusive users of Terminator armour.

This Honour appears most commonly as a skull set onto a cruciform shape of red iron or bone. Terminator sergeants often add crossed bones behind the skull, whilst lightning bolts behind the skull are often added for Terminators trained as Assault units wielding lightning claws and thunder hammers with storm shields. Variations include the size and dimensions of the skull and the removal of the crossed lightning bolts or bones or their scale in relation to the shape of the cruciform. The Crux Terminatus is almost always worn on the left shoulder pad, though it may also be worn on one knee pad (this is usually done only in combination with the shoulder pad, however). Legend has it that the first Crux Terminatus ever crafted contained a tiny fragment of the Emperor's own armour within it, an honour granted to commemorate a squad of Imperial Fists Terminators who aided the Emperor in the battle against Horus. Whether or not this is true it means that ancient suits of power armour bearing Terminator Honours are considered even more rare and precious to a Chapter as a result of their reputed connection to the Master of the Imperium.