Hailing from Poland, Gustav Krueger was given a bionic tail which he uses to create shockwaves and vibrations. The details and motivations of this are unclear. Krueger joined the Serpent Society, a mercenary organization for criminals styled around snakes, under the leadership of Sidewinder. During the Rattler's initiation into the Serpent Society, he and his fellow Serpents Cobra and Anaconda were ambushed by the hero Captain America, but Rattler was able to use his tail to stop Captain America's shield from doing any damage.