Character is easily one of the best, visceral and most badass I seen on tv (Travis Fimmel is such a scene stealer here, captured his inner struggles so well, despite questionable writing), more so because I'm very fond of history/iconic tales and no one has bothered to do Vikings to flesh like this (even if this show is a joke historically speaking). They managed to make Ragnar such a sly, sarcastic and intuitive character, could see the character come to life in so many small moments where he had completely unique perspective to things that was so different from what his culture expected of him at times.
Ivar and Björn will have a HUGE mantle to bear now, because Ragnar really was like 80% of this show, even when the shows writing detoriated so bad when they made him a delirious junky, he still had such magnetic presence in every scene that will be hard to recapture. Only actor and character that could take on this burden is Rollo (in some ways more badass), but his story is played out already...