Tylos Rubio

'Tylos Rubio was an extremely powerful Psyker during the Great Crusade era, who had once been a Codicier of the XIII Legion Ultramarines before the Emperor’s formal decree at the Council of Nikaea had banned the Space Marine Legion’s use of psykers, including their own corps of Librarians. Honouring his oath to the Emperor Tylos surrendered his Librarian panoply and wargear, returning to the lines as an ordinary battle-brother. He would later be recruited by Nathaniel Garro, a former Death Guard Battle-Captain, during the infamous Battle of Calth, becoming one of the seven Astartes that would help form the core of the Grey Knights Space Marine Chapter.