• Was a German–Danish portrait painter.
• Ziesenis' father Johan Jürgen Ziesenis was a painter from Hanover, who was granted Danish citizenship in Copenhagen in 1709.
• After drawing lessons from his father, Johann lived in Düsseldorf.
• In 1764, Ziesenis became court painter in Hanover and in 1766, he was granted 400 kroner by the Danish king "for travel and other expenses".
• In 1768, he was in The Netherlands, where he produced portraits of William V, his wife and family.
• Ziesenis created around 260 portraits and other paintings and sketches in the course of his life.
• In 1764, while in his sixties, he painted a portrait of Hans Egede.