Lucas Watzenrode (also, in German, Lukas; in Polish, Łukasz)(1400, in Thorn, Ermland – 1462, in Thorn) was the maternal grandfather of Nicolaus Copernicus.
Lucas Watzenrode the Elder was registered in the Thorn citizen registry book (Thorner Bürgerbuch) as landowner, businessmen, judge, councilman, etc., living at Seglergasse in Thorn. In 1436 he married Katharina von Rüdiger. In 1448 he and other Thorn burghers are registered as having been summoned to the court at Limburg.
Lucas and his wife Katharina had a daughter, Barbara, who married Nicolas Kopernik. Katharina's sister Christina married Tideman von Allen. Both sisters married in Towun.
Lucas Watzenrode the Elder's grandson became known as Nicolaus Copernicus. Copernicus had an uncle, his mother's brother, also named Lucas Watzenrode (known as Lucas Watzenrode the Younger), who as Bishop of Ermland strongly supported the independence of Ermland and helped rear Nicolaus and his brother Andreas after their father's death.
Christina and Tideman's daughter Cordula von Allen married Reinhold Feldstedt, who was born 1468 in Danzig and died 1529 in Danzig. Their daughter Katharina Feldstedt married Herman Giese, born 1523 in Danzig. A descendant was Tideman Giese, a famous bishop of Ermland.