Ida of Bernicia
Nennius in his Historia Brittonum wrote that Ida united Bernicia with Deira.  He also claimed that Ida was the first king of a united Northumbria 50 years before it actually happened. But Ida does not appear on any of the king's list for Deira. The king of Deira at this time was Yffi. According to the Anglo-Saxon Chronicle Ida had died by 560. Ida was succeeded by Glappa who reigned for one year.