10. Formed The Brotherhood Of Evil Mutants
No supervillain is complete without a team of loyal minions to back them up.
In Magneto's earliest appearances, he lacked a lot of his more nuanced character traits and was more of a traditional supervillain. Still, referring to your lackeys as "Evil Mutants" is a little bit on the nose.
The original Brotherhood consisted of the super-agile Toad, the illusion (not trick) creating Mastermind and unwilling members Quicksilver and Scarlet Witch, who had no idea that they were really Magneto's children (and now aren't because comic book continuity).
In their first appearance, the Brotherhood helped Magneto take over the country of San Marco by using Mastermind's abilities to disguise themselves as an invading army. They were of course stopped by the X-Men, but went on to help Magneto with various over evil schemes, like kidnapping Angel and sending Toad to infiltrate the X-Men.
They were also joined by new members, like the teleporting Vanisher, forcefield generating Unus the Untouchable and Blob, the amalgimation of ever "before" photo ever taken.
Eventually Scarlet Witch and Quicksilver rebelled against their guy-who-used-to-be-their-Dad-but-isn't-anymore and joined the Avengers. Soon after, the Brotherhood of Evil Mutants disbanded. Magneto went on to form a second team, but they all had the same mutant power of being impossible to care about.