The deaths of two people
A bunch of people died on Everest, but only two deaths really seem to matter to me. The first one is of Francys Arsentiev (sleeping beauty). She was the only person who's death impacted people so much that a guy went back up the mountain a few years later just to bury her. His team not only buried her, but also brought up with them letters from her loved ones to leave on her corpse.
The second death is of Lincoln Hall. He actually did not die on Everest, but rather later of cancer. It always bothered me that he survived being abandoned on Everest only to die of a disease he had no control over. Everest maimed him. He lost his fingers and parts of his face if I remember correctly. But he fought through the mountain to make it back home to his family. His story is featured on the TV show "I Shouldn't Be Alive" in episode "Left of Dead on Everest." During the filming of this episode he hadn't yet be stricken with cancer.