Magnetars are generally accepted as existing. Wikipedia suggests that the magnetic forces are strong enough to kill you.
I am assuming that virtually any spacecraft would have some magnetic properties vastly in excess of that its inhabitants. A steel hulled spaceship would thus be attracted to the magnetar long before its inhabitants would be threatened.
This brings up the question of avoiding a magnetar. Obviously, a spaceship with propulsion could just use its engines to offset the force from the magnetar. Given that the force between to magnets is proportional to the magnitudes of the magnetic poles, could we use an electromagnet to offset the intrinsic magnetism of the spaceship? The magnetar would essentially behave like a giant point source of magnetism at a distance. The electromagnet would need to be "pointed" at the magnetar to offset the force. Depending on the rotational velocity of the magnetar this could be challenging. As long as the spacecraft was not highly magnetic the electromagnet would not need to be significant in size.