Eric XII of Sweden
Eric "XII" was a rival king of Sweden, competing against his father, Magnus IV, from 1356 to his death in 1359. He was married to Beatrix of Bavaria, daughter of Emperor Louis IV.
In 1343 Eric and his brother, Haakon, were elected heirs of Sweden and Norway, respectively. That Haakon got the Norwegian throne in 1355 while Eric didn't get any position in the Swedish council might have affected his choice to lead a rebellion against his father in 1355. In 1357 the rebellion had forced Magnus to share Sweden with his son Eric who got to rule most of Southern Sweden and Finland. Sweden was reunited again in 1359 when father and son became reconciled, and co-ruled Sweden until Eric's death a few months later. Quite soon after his death his wife, Beatrix, died too. It is generally believed that they died of the Black Death.