The buff hottie Kendall Jenner encountered at the grocery store -- wearing a shirt suggesting her family should be killed -- has been ID'd ... and his contempt for the Kardashians is real.
TMZ has learned the guy with the jacked arms is Jason Christopher, and he tells us he had the shirt custom made a few years ago ... because he's not down with the Kardashian crew's affinity for wearing fur.
Jason says he's a vegan and an animal lover, and his shirt is simply a way to protest the family's values.
As we reported ... Kendall was out to grab some milk at the market Wednesday when she saw Jason and his "Kill the Kardashians" shirt and shared a video of him on her IG, which quickly went viral.
Interesting note -- this isn't the first time he's made headlines. In January 2016, he was reunited with his stolen dog, Bronson, a Chihuahua who was famous for appearing in a 2014 Scrubbing Bubbles commercial.