I've recently watched both of these documentaries (on Netflix streaming) and enjoyed both quite a bit. Both have to do with "urban legends" and how they tend to get their start from true life events.

Cropsey (2009) is about the murder and disappearance of several children on Staten Island and how it led to the urban legend of Cropsey, the maniacal boogeyman that used to scare the filmmakers as children. 7/10

Killer Legends (2014) is in the same vain as Cropsey, but it covers several different urban legends and the events that may have inspired them. 8/10

I enjoyed Killer Legends more, simply because I liked hearing about the different stories. Crospey was interesting, but it got a little stale near the end. Both are from the same filmmakers, so they both have the same style and tone, which I liked.

I'd recommend both to anyone interested in the subject matter or anyone who just wants to watch a good documentary.