5Umaga
Source: wwe.com
Umaga was a two-time WWE Intercontinental champion and a huge part of the WWE world. His most famous feuds were against John Cena and D-Generation X. However, he suffered a heart attack when he was only 36, and that got him killed. The unfortunate event happened in 2009 and Umaga was apparently using illegal substances, which were a cause of his death. He was one of Dwayne Johnson’s cousins.