"You once more managed to succeed, on an impossible mission, WHEN YOU SHOULD HAVE DIED!... But NO! You succeeded because you were trained by the book, the holy codex of our OH-SO-WONDERFUL-I-COULD-SHIT-MY-POWERPANTS SPIRITUAL LEIGE!"Marneus Calgar is the current Chapter Master of the Ultramarines.
Official Canon Edit
Marneus Calgar is one of the best known Chapter Masters in the Imperium, being the leader of the Ultramarines and the Ultarmar region of space. During the invasion of Macragge, he lost all his limbs after fighting the Swarmlord, with his entire first company getting killed trying to rescue him. Nonetheless he was able to escape and rout the Tyranids from Ultramar.
TTS Canon Edit
Unfazed by losing all his limbs to the Swarmlord, Calgar decided to call the duel a draw. However, witnessing the horrible destruction, including the deaths of the entire First Company, left a lasting impact on Calgar.
Despite this, the Ultramarines simply won the battle offscreen and for no adequately explained reason. Since that point onward, the Ultramarines have won every battle they've fought in, even if they should have been impossible. Even their past failures seem to have been retroactively altered so as to cover them up. This repeated winning streak has caused Calgar to enter a depression spiral as victory comes too easily now and has lost all satisfaction. He is also bitterly annoyed by the existence of Cato Sicarius, who is constantly trying to usurp him as Chapter Master. Even more, he hates that Sicarius didn't care at all about needlessly putting his men's lives at risk.
Uriel Ventris, one of Calgar's confidents, confesses that he believes something is altering the past in the chapter's favor. Acting suspicious, Calgar vehemently denies this, while claiming he wasn't hiding anything.
The Ultramarines' strange reality-bending competence was demonstrated once again when Calgar was able to easily leap into the air despite wearing bulky Terminator armor, claiming he didn't need a Jump Pack (though this is more of a joke referencing Gabriel Angelos doing the same in Dawn of War 3 despite this being nominally impossible to do with a Terminator suit).