Magnets do a lot more than stick on your refrigerator. The strongest manmade fields make particle collider and fusion reactions possible. But, as we shall see, our best efforts pale in comparison to magnetic fields in the far reaches of the universe, like those emanating from neutron stars.
Different kinds of supernovae produce different results. The largest supernovae leave black holes in their wake, but slightly less massive ones create neutron stars. These stars are incredibly dense, and incredibly magnetic: While the Earth lackadasically maintains a magnetic field of about 0.5 gauss, a neutron star's field measures in the trillions. This one is Cassiopeia A, imaged by the Chandra X-Ray observatory.