Claim: King Duncan was played by David Thewlis.

David Thewlis -LRB- born David Wheeler ; born 20 March 1963 -RRB- is an English actor , director , screenwriter , author . His most commercially successful role to date has been that of Remus Lupin in the Harry Potter film series . Other notable performances include the films Naked -LRB- for which he won the Best Actor award at Cannes Film Festival -RRB- , Dragonheart , Kingdom of Heaven , The Boy in the Striped Pyjamas , The Theory of Everything , Black Beauty , and Macbeth -LRB- in which he played King Duncan -RRB- . He will play Ares in Wonder Woman . He has also done voice work in the films James and the Giant Peach -LRB- 1996 -RRB- , The Miracle Maker -LRB- 2000 -RRB- , and Anomalisa -LRB- 2015 -RRB- , and is additionally known for the role of Cyrus Crabb in the TV mini series Dinotopia .