7. Killer Couples
I honestly, can’t fathom how Killer Couples not only had so little reviews on Netflix, but I couldn’t even find the title on IMDb, either. With only 10 ratings to go by, this British docuseries still came out with a solid 2.0 out of 5 and still one of the best serial killer documentaries on Netflix—hands down! Mark Billingham, a well-known writer of fictitious crime novels (also comedian/actor/producer… what doesn’t the guy do?) takes us on a journey with some deranged duos. What sets these true stories apart from, well, any other documentary on this list is how Mark exposes the rare cases of when these sick minds come together to create an often sicker set of psychos and tries to find a better understanding of the relationship between them.