Superconductor
Normally, a magnet moving by a conductor produces currents in the conductor by electromagnetic induction. But a superconductor actually pushes out magnetic fields entirely by inducing surface currents. Instead of letting the magnetic field pass through, the superconductor acts like a magnet pointing the opposite way, which repels the real magnet. This is called the Meissner effect, and it can be demonstrated by levitating a superconductor over magnets or vice versa.