A negative person

You call such a person a jinx.

Lightning rod, figuratively a "person or thing that is a target for negative reactions and distracts criticism from another target" is an alternative to jinx, a "person or thing supposed to bring bad luck", as is jonah, a "person or object which is deemed to cause bad luck; a jinx".

All of these are used in context alongside the idea of "luck" or that this person is simply a victim that attracts negative situations. If you're trying to describe the person as having a negative disposition (and possibly causing his/her own suffering) then you may use these idioms. However, idioms are strictly informal, use caution in professional settings.

Negative people can be called

• Debbie Downer
• Susie Raincloud
• Negative Nancy
• Grumpy Gus

These refer to disposition rather than situational negativity...I don't know if this helps.