Which actor played the role of Joker in the movie Batman?
role of Joker refers to character_name = 'Joker'; movie Batman refers to title = 'Batman'
SELECT T3.Name FROM movie AS T1 INNER JOIN characters AS T2 ON T1.MovieID = T2.MovieID INNER JOIN actor AS T3 ON T3.ActorID = T2.ActorID WHERE T1.Title = 'Batman' AND T2.`Character Name` = 'Joker'