Who was the actor that played in the movie "Batman" with the longest screentime?
movie "Batman" refers to Title = 'Batman'; longest screentime refers to max(screentime)
SELECT T2.Name FROM characters AS T1 INNER JOIN actor AS T2 ON T1.ActorID = T2.ActorID INNER JOIN movie AS T3 ON T3.MovieID = T1.MovieID WHERE T3.Title = 'Batman' ORDER BY T1.screentime DESC LIMIT 1