I think the Sharon Tate/Manson murders were the most horrific, but there have been so many horrible deaths.
The Kobe Bryant one is awful; when you read what happened to them, you hope they died instantly.
Roger Williamson, F1 driver, died horrifically in a crash; he had a colleague who rushed to help but couldn't get close due to the flames and Williamson died within a few feet of people who could do nothing but watch.
I only found out yesterday that Christopher Plummer died after falling down some stairs and cutting his head.
The actress Isadora Duncan died after her scarf got wrapped around the wheel of her car; when she went to drive away, she broke her own neck.
Anton Yelchin getting crushed by his own car was awful.
Tommy Cooper dying on stage was probably what he would have wanted but having people laughing as he died was horrible.
Natalie Wood, who was afraid of water, was most likely murdered on a boat and thrown overboard.
Chris Farley died of an overdose but his last words were to a prostitute begging her not to leave him alone, apparently.
Jim Henson was coughing up blood but didn't want to go to the hosptial. If he'd have gone, he'd have been fine. Instead he died within 24 hours.