Professional safecracker given early release from prison in exchanging for teaching his skills to Maxwell Smart.
Ballantine was so skilled that when he first went to prison they had to weld him into his cell. When KAOS planned to rob a bank, they wanted to hire him to do the job. However, wishing to go straight, Ballantine informed the authorities.
What happens after his release is unknown, but (like fellow safecracker Simmons three years later) he mentions plans to become a TV repairman. Max is surprised by this, saying, "I thought you were going straight."