Who killed Shah Jahan?

Although not directly, Aurangzeb was responsible for Shah Jahan’s death indirectly when he dethroned his father in 1658 on the grounds of illness. Despite Shah Jahan recovering, Aurangzeb still had him imprisoned until his death in 1666. 

For further reading check the following articles:

• Akbar’s Successors
• List of Mughal Emperors
• Mughal Empire in India