A teenager who moves so much faster than everyone else that the world is, to him, a room full of statues he can rearrange.
Peter Maximoff is the answer to a question the films had not asked: what does speed actually look like. The Pentagon kitchen sequence in Days of Future Past stops the world, puts a song on, and lets him take his time, and it is the most copied thing in the series.
Apocalypse runs the same idea across an exploding mansion and adds the reason he is there: Magneto is his father, and he has not worked out how to say it.