King River Johansen-Butterfly (voiced by Alan Tudyk (adult) and Sonny Ashbourne Serkis (young)) was the King of Mewni and Star Butterfly's father. A member of the Johansen family, he married Moon and took her family name. The Johansens are portrayed as rough, Viking-like barbarians fond of the outdoors and fighting who allied with the forces of Mewni in the war against the lizards lead by Toffee. River is of a stout, broad physique, sports a full beard, and is fond of wearing no clothes other than a loin cloth made of leaves. He is shown to be physically strong and a relatively bold, inspiring military leader, but was a poor administrator when left in charge of Mewni in Moon's absence.
