Well, Tamani does come to mind. A lot of people have stated their disdain for her, though my only beef with her is not so much Tamani herself, just that her encounter rate does seem at time very up and down. Sometimes, she'll show up nearly every time you explore the forest or deepwoods, sometimes she seems completely gone (and that's in between pregnancies). Moving her to "Places" seems like a better suggestion than simply adding a "never encounter again" button like many have suggested before in the past. She's gotta sleep somewhere, so adding some sort of hideout where she and her daughters call home when they are not out and about looking for you wouldn't be completely out of the realm of possibility.