Born abt 1340. Parents: Albrekt II, Duke of Mecklenburg and Eufemia of Sweden (sister of Magnus Eriksson).
King in February 1364. He was never crowned. From 1384 Duke regnant of Mecklenburg. Defeated in Falköping in February 1389. After being deposed as King of Sweden, he returned to Mecklenburg, where he died in 1412.
The Swedish nobility had him elected, but if wasn't untnil 1371 that all his opponents were defeated. By that time he had lost most of his power. When he tried to regain his power, Margareta was elected Queen.
Married 1. in 1365 to Rikardis (died 1377), daughter of Otto, Count of Schwerin. Children: Erik (born in the late 1360's, died 1397), Rikardis.