Vikings: Every Character Based On Real Historical Figures

Ecgberht was the King of Wessex and the father of Aethelwulf, who succeded the throne after his death. That is pretty much where the similarities between the show and reality end.

There is no evidence of him having the close connection to Ragnar Lothbrok. The historical figure died of natural causes, he did not commit suicide and he was not under attack by Ragnar's sons at the time.