Originally posted by Wafflesaurus Supreme:

When a wraith finds you, mark it on the map. They'll respawn in the same area. Same with serpents.

I believe this is some really old information as i've never had them spawn in the same area. I checked it a dozen times, put down markers, never spawned in the same area again, yeah once but that was most likely just a coincidence. The only ones i noticed were trolls, they spawn close to troll caves in an x radius around them. Kill one, x days later a new one spawns in that radius.