David Haskell John/Judas
The one thing that confused me with the movie is why did they use the same actor for both John the Baptist and Judas?
It seemed such an odd decision.
Is it something to do with the original source theatre production?
They needed a John the Baptist character to kick off the story and then initiate the reprise of "Prepare Ye.." so he played double duty as Judas as well. That reprise of "Prepare Ye.." seems an obvious choice in retrospect, but a brilliant one. And that was a suggestion of Stephen Schwartz.
And yes, it goes back to the stage version.