Refrigerate: do you need to refrigerate a pecan pie?

No, pecan pie is perfectly good safe at room temp. Unlike fruit pies, which can sit out two days but then in fridge for three days.

If you're serving it on the day and the weather isn't too hot, room temp would be the best way to maintain the crispness in the pastry. As for overnight however...I would most probably refrigerate it for the sake of food safety, although I have kept it at room temp before and it was perfectly fine.