The Zodiac Killer (1971) **

As a piece of cinema history, 1971's The Zodiac Killer is an interesting curio that serves as the first film to reference the famous serial killer (supposedly made in an attempt to catch Zodiac) that gets some of the facts of the (still) unsolved case correct but mostly plays fast and loose. As a movie, it's a hilarious, melodramatic, low budget mess that meanders and baffles in equal measure. 

If you want to laugh at the casual misogyny, homophobia, and terrible acting, The Zodiac Killer is actually pretty entertaining—as if Herschell Gordon Lewis tried to make a serious film (as my friend Rob put it). If you want a good film based on Zodiac, you're better off sticking with 1971’s Dirty Harry (admittedly more tangentially based on the case but excellent nevertheless)—released later the same year—or David Fincher's 2007 masterpiece Zodiac.