Whereas The Disaster Artist is a fictional retelling of the making of The Room, Best Worst Movie is a documentary.  It depicts how what is affectionately known as the worst movie ever, Troll 2 (currently with a 6% on Rotten Tomatoes, and having no relationship to the movie Troll), became a cult classic eighteen years after its 1989 release.  Best Worst Movie starts with a visit to the hometown of Alabama dentist and Troll 2 lead actor George Hardy.  Almost unbelievably likable, Hardy takes viewers along as he takes breaks from dentistry to attend sold-out Troll 2 screenings in places from Los Angeles to Austin.  

The movie also shows interviews with the Italian filmmaker Claudio Fragasso and his wife, who wrote the screenplay, and shows their belief that they were making important, groundbreaking cinema (not unlike the sincerity of Tommy Wiseau in making The Room).  Upbeat and hilarious, this is a perfect companion piece to The Disaster Artist.

Bonus: If you liked The Shape of Water

Mrs. Caliban is a recently rediscovered 1983 novella about a depressed housewife who falls in love with a frog-like creature escaped from a nearby research facility.  Sound familiar?