Nicoletu and the Face-Stealer

A 5th century BC account of a Barovian man's encounter with a (alleged by some) doppelganger, and the only such alleged account of an encounter with a doppelganger prior to Paridon's entry into the Mists in 551 BC. However, it is likely this story originally referred to a Skin Thief and was merely embellished by later outlanders, at least according to the analysis in Van Richten Society Research Files: Doppelgangers.