According to the author Peter Underwood, a shop in Twr, Bethesda, was once haunted by ghost of the 17th century Dr John Williams, who was incarcerated in the Tower of London for perjury, later to be released and made Archbishop of York. It was said he haunted the shop because he had a substantial amount of money buried in the garden of the property.
For further information, please read Haunted Wales by Peter Underwood.