The Death of Deborah Stone: On July 8, 1974, 18-year-old Disneyland employee Deborah Stone was crushed to death between a revolving wall and a stationary platform inside the America Sings attraction. She was standing in the wrong area during a ride intermission and was trapped and crushed by the wall when it came down. The incident might have been due to inadequate training, as the ride had only been open for two weeks at the time.
Seriously though I am surprised deaths don't happen more often. The Walt Disney parks had 132,549,000 visitors just in 2013. So just in that year alone the average was more than 37 thousand people per day.
I'll bet you it is statistically safer to play and have fun inside their parks than the trip flying or driving there.