Otto, Duke of Brunswick-Grubenhagen

Otto of Brunswick-Grubenhagen (c. 1320–1399), called the Tarantine, was the eldest son of Duke Henry II. With little to inherit, he became a bold condottiere. His marriage to Violante of Vilaragut, widow of James III of Majorca, made him the richest member of his family.

In 1376 he married Queen Joanna I of Naples, her fourth husband, and became Prince of Taranto, though not king. The couple backed the Avignon pope, and when Charles of Durazzo took Naples in 1381, Otto was captured trying to free the queen; she was strangled in prison in 1382.

Freed in 1384, he won Naples back for Louis II of Anjou in 1387, but, passed over for command, joined the Durazzo side. He died at Foggia in 1399, having rarely seen Grubenhagen again.