Mysterious vendors are a place or person that sells unusual, rare, or magical items and artifacts. They may be found in street markets, in alleyways, or in the slums. They may travel from town to town. They may be shops that, once found, can never be found again. They may sell cursed, magical, or illegal goods. This may be a place to find an alien artifact, a treasure map, a book of magic, or a fantastic creature. They may only accept promises, items, or other valuable things rather than typical currency.
The shops of mysterious venders are often depicted as cluttered, with unusual items scattered about. They may be located in a hidden market.