Charlie Hunnam and Astrid Bergès-Frisbey are already at the top of the cast as Arthur and Guinevere, but Guy Ritchie's upcoming Knights Of The Round Table: King Arthur is now gathering more players. Just arrived on the field of battle is Swedish actor Mikael Persbrandt. If the name's unfamiliar, you may know him as The Hobbit's shapeshifting Beorn.Persbrandt won't be sitting at the Round Table, however, since the word from the marshes of medieval England is that villainy is in store for him. Unconfirmed reports give him the role of Kjartan, a Viking envoy in cahoots with the film's bad guy Vortigern.Last we heard, Eric Bana was also aboard to play Arthur's father Uther Pendragon, with Ritchie's Dr. Watson Jude Law in talks for Vortigern and Djimon Hounsou circling the role of Sir Bedivere.The rest of the plot is largely shrouded in mystery, though Edge Of Tomorrow...