Björk has joined the cast of “The Lighthouse” director Robert Eggers’ next film “The Northman,” which has begun production in Ireland and boasts a cast that includes Nicole Kidman and Willem Dafoe, an individual with knowledge of the project told TheWrap.The Icelandic singer will play a character known as “The Slav Witch” in Eggers’ film, which is a viking revenge drama set at the turn of the 10th century.