Typhus

"'Do you know what a CLIT-ORIS IS!? ...Me neither. BUT IT SOUNDS DISGUSTING!'"Typhus is First Captain of the Death Guard, and a champion of Nurgle.

Official Canon
Typhus was originally Typhon, an ordinary Death Guard legionnaire until he learned of Chaos through the workings of Erebus from the Word Bearers. A secret Psyker, Typhon sold his soul to Nurgle to become First Captain, and helped engineer the downfall of his Primarch Mortarion. When the Death Guard killed all their Navigators, Typhon offered to navigate the ship, leading them directly into a destroyer plague that was only stopped when Mortarion and his men swore their lives to Nurgle.

Typhus wants to spread Nurgle's love to every living being in the galaxy, being so diseased-ridden that he can liquefy lesser beings.

TTS Canon
Typhus reads excerpts of SQUAD BROKEN as a favor to Lucius the Eternal. He has joined the other chaos champions as part of Abaddon's call for a new Black Crusade. He also appeared as a guest on the Slaaneshmas special.

Trivia

 * Typhus' first appearance is largely a reference to this skit where Gilbert Gottfried reads 50 Shades of Grey, right down to his pronunciation of "Clit-TORUS!"