In 1956 Clifford Brown and Richie Powell were traveling through Pennsylvania on their way to Chicago to play a date with Max Roach. Richie's wife was driving. They had an accident and all three were killed. Clifford was only 25. I don't know what qualifies one to be termed a "giant" but, if he wasn't one, he certainly stood on the top rung of the jazz ladder playing regularly with all of the heavyweights of the time.