"The death of others is a small price to pay, as they fall, performing their duties in order to achieve glory for the interest of the best Ultramarine Captain - which of course is I, Cato Sicarius!"Cato Sicarius is the Captain of the 2nd company of the Ultramarines, Master of the Watch, Knight Champion of Macragge, Grand Duke of Talassar, and High Suzerain of Ultramar.
Official Canon Edit
Hailing from Talassar, he would join Ultramarines as an aspirant and go onto become a sergeant and eventually Knight Champion of Macragge. He would assume the rank of Captian of the Second Company after the Tyranids effectively ate his predecessors.
He would engage in many campaigns across the Imperium and gaining a reputation as a True Hero of the Imperium (as far as he is concerned, anyway), fighting in the Dantaro Campaign, on Masali, Medusa IV, Black Reach, Damnos: and many more. He would eventually gain a reputation as the likely successor to Marneus Calgar as the Chapter Master, despite the Codex Astartes stating that it is normally the First Captain to be the chosen successor.
In the new Gathering Storm Lore he was present on Macragge to witness the revival of Roboute Guilliman and would accompany him to Terra.
TTS Canon Edit
Sicarius is an insufferable glory hound who speaks in a falsetto voice, and always refers to himself as "I, Cato Sicarius." He is the personification of everything wrong with the Ultramarines, as he flawlessly executes otherwise impossible missions with the greatest of ease and in the most obnoxious manner possible. He was able to capture Magnus the Red without his Gellar Fields active, and found the artifacts of Vulkan in less than a year. Marneus Calgar especially hates him, as Cato has made it abundantly clear that he wants to become the new Chapter Master despite Calgar still being alive.
Cato also wrote a fanfic about himself, where he effortlessly defeats mankind's enemies, including the four Chaos Gods, and is appointed the new Emperor of Mankind. When he had finished writing it, the Emperor burned his drafts before he could publish it.