Marneus Calgar

Marneus Augustus Calgar is Chapter Master of the Ultramarines and Lord of Macragge, the mortal face of Guilliman's Legion for the centuries the primarch spent as a relic. He lost the first war for Macragge's polar fortresses, won the rest, and learned to govern Ultramar as well as defend it.

He crossed the Rubicon Primaris after his gene-sire returned, because the Lord Commander asked and because Calgar does not like to be the thing that cannot adapt. On Vigilus he baited Abaddon into a duel so an Eldar-laden missile strike could cripple the Vengeful Spirit. He nearly died for the trick. It worked.

Guilliman has called him a point of light in a dark age. Macragge still treats that as an order, not a compliment.