The biggest tragedy in golf. Jean van de Velde's collapse at the Open Championship at Carnoustie in 1999. A double bogey 6 or better was all that seperated the Frenchman from the Claret Jug. He made a 7!!!!!! He lost the resulting 3 way playoff to local hero Paul Lawrie.
I uploaded this video as Carnoustie which is currently holding the Open, will always remind me of Jean's antics at the last.
I have a blog entry of the tragic event. You can find it here