Ivan the Terrible is a fascinating character, to the extent that politicians touched by paranoia can be fascinating.

The mad tsar is played by Pyotr Mamonov, who did a splendid job in Ostrov / The island (2006).

The plot of the movie reminds me of A Man for All Seasons, which also pits a tyrannical (but not quite so mad) monarch against the upright prelate bound to his conscience and to God.