John Wilson (Swedish sailor)

John Wilson was the Anglicized name of Captain Frederick Walgren, (8 July 1851-5 August 1899) a Swedish sailor and o-yatoi gaikokujin (foreign professional) who was active in the development of British-Japanese ties in the late 19th century.

Walgren was born in Genarp, Skåne, Sweden on 8 July 1851. He entered into British service, changing his name to Wilson. Wilson initially resided in Nagasaki, Kyūshū, living next-door to Thomas Blake Glover. The Wilson family subsequently resided in Nagasaki and Kobe. He married a Japanese national on 11 January 1883 at Christ Church, Yokohama, the Anglican church located in Yamate, overlooking the Port of Yokohama, Japan. His wife (b. 5 July 1860) upon baptism Anglicised her name from Naka Yamazaki to Sophia Wilson, and adopted her son, Nils Wilson. Their children were August, Frederick, Maria, Christina, Hilda, Hannah and John.

Sofia Wilson was a confidant and neighbor of Tsuru Glover, the Japanese wife of Thomas Glover, and together with Tsuru's friendship with the Japanese Ambassador to Italy, the stories of Naka and Tsuru may have been incorporated in Giacomo Puccini's Madam Butterfly.