Brazilian F1 driver Senna's is perhaps the most famous on-field death in sporting history. The 3-time world champion was a legend in the sport even before his untimely death at the 1994 San Marino Grand Prix. Leading in lap 6, Senna collided with a wall at 135 mph while taking a turn. Despite being air lifted and rushed to hospital, Senna had suffered significant blood loss and trauma and was later declared dead. God only knows how many more championships Senna would've won if this mishap had not taken place!