Meet Eddy, the current. The U.S. National High Magnetic Field Laboratory in Tallahassee, Florida operates the world’s most powerful magnet, with a magnetic field of 45 Tesla. By comparison, the Earth’s magnetic field is 32 microtesla (μT), a refrigerator magnet is around 5 millitesla, and the beam steering magnets at the Large Hadron Collider are 8 T.
(Illustration by Noles1984 at English Wikipedia, CC BY-SA 3.0, File:National High Magnetic Field Lab00.png - Wikimedia Commons).
Interestingly, the 45 T magnet is a composite of a superconductive magnet and a resistive magnet, configured so their fields add. A purely superconductive magnet would break down and cease to superconduct under the full field generated by the magnets. When all power supplies are running, the laboratory consumes 8% of the electrical power of the city of Tallahassee.