Doppelgangrel

The Doppelgangrel is a xenos beast with chameleonic abilities that make it virtually impossible to catch, much less kill.^[1]

The only known person to have done so is the famously crafty Lukas the Trickster, a Blood Claw of the Space Wolves Chapter. Lukas wears the beast's skin as a cape, and its chameleonic effects make it all but impossible for him to be hit with a ranged or melee weapon.^[1]