Edward: Dies in a battle

Alice: Dies of stress of trying to see the future

Jasper: Dies of making himself so happy that he explodes

Rosalie/Jacob: Dies of falling in love and their kiss made the static in their lips so strong that it electrocutes them

Emmett: Dies of suicide of not being able to live without Rosalie

Nessie: Dies of old age

Bella: Doesn't die. She marries a unicorn instead