Erik Lensherr / Magneto

Main Comics (616)
Later, Rogue fell in love with Magneto's clone Joseph. After that, to quote one fan, "she kept throwing herself at Magneto over and over...The more he turned her down, the more attached she became to the idea of them being together until it actually got rather pathetic. (Lobdell) (also see Adi Granov's cover for X-Men: Legacy #232)
 * 1)  Natalya Maximoff -  Before his days as Magneto, Erik carried on a love affair with this Eastern European woman, before a lynch mob, having discovered he was a mutant, attacked and apparently killed her. This only fueled his hatred for the human race. Natalya, in fact, lived long enough to give birth to Erik's twin children, Wanda and Pietro Maximoff, before dying. He would only discover his children when they were adults.
 * 2)  Janet Van Dyne / Wasp  and Magneto had a brief fling during the events of the first Secret Wars.
 * 3)  Rogue  and Magneto shared the beginnings of a relationship while in the Savage Land. (Uncanny X-Men #274, Claremont).

X-Men Movies

 * 1)  Raven Darkholme / Mystique  - Magneto and Rogue have a sexual relationship as members of the Brotherhood. in the initial film trilogy. In First Class, we see how they were attracted to each other, and shared a kiss, while he and Charles were forming the initial X-Men team. She then chose to go with him when he split apart from Charles to form the Brotherhood.

Years later (in Days of Future Past) however, she was no longer by his side. Although she would have returned to the Brotherhood in the normal timeline, it was at this point that the Wolverine from the future arrived, creating a new timeline. In this new series of events, Raven turned away from the side of villainy and became an X-Man. Erik too seemed to shake his evil side, although they did not become a couple after this.