“Every gray hair on my head I call Kinski,” laments German maverick director Werner Herzog in My Best Fiend, a revealing and shockingly funny reminiscence about his volatile collaboration with notoriously ill-tempered actor Klaus Kinski. A shared, borderline-maniacal passion for cinema may have been the only thing that kept the pair from killing each other, but their five features together—including Aguirre: The Wrath Of God, Fitzcarraldo, and Nosferatu—harnessed their personal friction into something special. Given enough distance from Kinski’s death in 1991, Herzog’s reflections on their partnership take on a disarmingly bittersweet tone, even as he recounts one appalling tantrum after another. A mix of archival footage and awkwardly staged “conversations” with former cast and crew members, My Best Fiend travels back to old haunts, from Herzog’s childhood home to the Peruvian jungles of Aguirre, and tells some great Kinski stories. Many would seem like outrageous embellishments if Herzog weren’t so dead earnest, or if he didn’t have a queue of witnesses to back him up. A few incidents are linked to Kinski’s exceptional capacity for rage, which once led the young actor to demolish an entire bathroom (tub included) in a sustained 48-hour screaming fit. Others are ego-driven, such as a dinner that ended with him hurling hot potatoes and cutlery at a theater critic for referring to a minor performance as merely “excellent” instead of “monumental” or “epochal.” Most are some toxic combination of the two. Kinski reserved his worst behavior for Herzog, but their mutual willingness to suffer for their art led to electrifying moments onscreen. In one clip lifted from Les Blank’s excellent Burden Of Dreams, a documentary about the making of Fitzcarraldo, Herzog shows a bell-tower scene with his original choice for the title role, the brilliant actor Jason Robards, then the same scene again with the wild-eyed Kinski. No comparison. My Best Fiend is, in the end, Herzog’s affectionate tribute to the only person on Earth who could claim to share his insane level of dedication.