Helbrecht

"'NO! MY HEAD IS HERESY! LOATHE THE HAIRLESS HEAD FOR IT IS IMPURE!'"Helbrecht is the High Marshall of the Black Templars.

Official Canon
As commander of the Black Templars chapter and its massive fleet, Helbrecht commands the Imperium's largest Space Marine force available. He personally commanded all orbital forces during the Third War of Armageddon and has sworn personal revenge against Ghazghkull Mag Uruk Thraka.

TTS Canon
Helbrecht was summoned to the Imperial Palace by The Emperor to try to convince him that he and his chapter should get their anger under control and to stop hating otherwise loyal psykers and mutants. Helbrecht was at first furious at being summoned by warp magic and refused to listen until the Emperor forced him to calm down. At first Helbrecht was unwilling to see the error of his ways, until the others in the palace started fighting among themselves. It was only after that, with much reluctance, that he submitted to the Emperor's decree that the Black Templars would be joined by not just Space Marine Librarians, but also Sanctioned Psykers and Ratlings.

Trivia

 * Helbrecht's voice takes after his portayal in the audiobook version of Helsreach by Aaron Dembski-Bowden.