Don't F**k with Cats: Hunting an Internet Killer is a 2019 true crime docuseries about an online manhunt. It is written and directed by Mark Lewis and was released on Netflix on December 18, 2019. The series chronicles events following a crowd-sourced amateur investigation into a series of animal cruelty acts committed by Canadian pornographic actor Luka Magnotta, culminating in his murder of Chinese international student Jun Lin. It was one of Netflix's Top 5 most-watched documentaries of 2019.

In May 2012, Jun Lin, a university student, was fatally stabbed and dismembered in Montreal, Canada, by Luka Rocco Magnotta, who then mailed Lin's hands and feet to elementary schools and federal political party offices. After a video depicting the murder was posted online, Magnotta fled Canada, becoming the subject of an Interpol Red Notice and prompting an international manhunt. In June 2012, he was arrested in an internet café in Berlin. In December 2014, after eight days of deliberations, a jury convicted him of first-degree murder. Magnotta was given a mandatory life sentence and 19 years for other charges, to be served concurrently. Magnotta was previously sought by animal rights groups for uploading videos of himself killing kittens.