First Appearance - Batman Beyond (Animated TV) S3 Ep2 "Untouchable" (Sept 2000)
The Repeller was a mercenary who wore a suit that repelled all matter. In reality, he was Dr. Suzuki, a scientist working at Wayne-Powers Medical Research.
Together with Dr. Blades, Suzuki strove to improve isolation environments for those born with a defective immune system. They developed the ISO field generator rings which created a protective aura allowing its user to interact in an outside environment.
Dr. Suzuki saw the lucrative possibilities of the diagravitational rings, but considered that Blades was too short-sighted to understand it. So, he purchased power-boosting servo circuitry, forging Dr. Blade's signature, and secretly enhanced the power of the Rings. Then, Suzuki decided to make a profit out of this powerful weapon, and became a burglar for hire for a terrorist cell to steal three rare Isotopes ? Alpha Sterilium, Beta Sterilium, and Gamma Sterilium.
Donning the enhanced ISO field generator rings, Suzuki was virtually unstoppable and invincible. He had an impenetrable aura that enabled him to withstand any impact, and survive in any kind of aggressive environment. Suzuki could also concentrate and channel energy down his palms, thus emanating powerful repelling and destructive bolts. Finally, the anti-gravitational properties of the Rings allowed him to levitate.
Batman eventually defeated Repeller by activating a giant turbine that generated so much noise that Suzuki was forced to deactivate his aura, giving Batman the chance to apprehend him. (via dcanimated.wikia.com)