Who was the most famous king of the House of Griffins, and King of Sweden, Denmark and Norway in the 14th and 15th centuries?
House of Griffins:  The most prominent Griffin was Eric of Pomerania, who became king of the Kalmar Union in 1397, thus ruling Denmark, Sweden and Norway. Eric of Pomerania: Eric of Pomerania KG (1381 or 1382 – 24 September 1459) was King Eric (Eirik) III of Norway (1389–1442), King Eric VII of Denmark (1396–1439), and King Eric ("Ericus") of Sweden (1396–1439), in all three known mainly as "Erik af/av Pommern".
Eric of Pomerania