Perturabo
Primarch of the Iron Warriors.
Greatly known for his mastery of siege warfare. He is feared for his status as a Daemon Prince. In other words,he's one big, mean and badass motherfucker who knows how to make the strongest thing go down.
Whats also known about him is his rivalry with Rogal Dorn. What we know about these two is that their quarrels is equivalent to the typical sibling rivalry.While Dorn's Daddy's Golden boy,Perturabo serves as the incredibly jealous brother who just wants to tear his brother limb from limb.This is probably what started the rivalry with the Iron Warriors and Imperial Fists.