Otto, Duke of Brunswick-Grubenhagen
Otto , Duke of Brunswick-Grubenhagen ( 1320 – 1 December 1398 ) was the fourth and last husband of Joanna I of Naples . 
<triplet> Otto, Duke of Brunswick-Grubenhagen <subj> Joanna I of Naples <obj> spouse <triplet> Joanna I of Naples <subj> Otto, Duke of Brunswick-Grubenhagen <obj> spouse