Kor'sarro Khan
Kor'sarro Khan is what you would get if Genghis Khan rode a motorcycle.
He is the captain of the White Scars' 3rd Company, and the Master of the Hunt for the White Scars. He wields a special relic blade called Moonfang and rides a bike called Moondrakken. Sammael wishes he was this cool. Because riding around on the last Imperial Jetbike, rocking an AP2 Sword, Eternal Warrior, and a fucking plasma cannon, must totally suck compared to a fancy bike and power sword.
He's also one of the few non-white characters in the Imperium. On the tabletop, he makes space marine bikers troops (which isn't unique, any Captain on a bike can do that), but more importantly, gives his bike-mounted command squad Hit and Run and Furious Charge. He has also killed Doomrider - wait, what?