D E A N
You got stabbed by a demon and died in Dean's arms before he could get you to a hospital.
S A M
You died the same way Mary and Jess died.
C A S T I E L
Naomi had sent angels to track you down and kill you. You were stabbed multiple times with an angel blade.
G A B R I E L
Sam had killed you to get revenge for his brother, Dean. He had shot you in the head, resulting in a quick death.
L U C I F E R
Crowley's demons had gotten to you before Lucifer could save you. You were stabbed multiple times in the stomach.
B A L T H A Z A R
Lilith killed you after a hunt went bad. She snapped your neck.
A D A M
A drunk driver hits your car head-on. After that, you fall in a coma. You died after five years.
C H A R L I E
A demon had possessed your body. After using you for a few days, you were left very weak and you didn't survive.
C R O W L E Y
Another demon had ripped your heart out right in front of him.