Caminante Nocturno This movie was most likely someone's D&D campaign adapted to a script, which is something I wish would happen more often.
Modern Angel Most 80s fantasy movies were quite obviously a D&D campaign given life. This movie is amazing.
Nikon I agree with Caminante. At one anime con I attended a panelist said she didn't like the Lodoss War OVAs or Slayers because both owed their existence to TRPG campaigns. That panelist must have been on some powerful drugs.