As the appellation suggests, a forger named Freddy.
When the Chief and Larabee are accidently locked in a bank vault with a delayed timer and a limited air supply, the Chief sends Max and 99 to the prison where Baffles, reputedly the greatest safecracker in the world, is incarcerated, with an offer of freedom in exchange for opening the vault.
Sadly, they are too late, arriving just minutes before Baffles is apparently executed.
Desperate, they offer the deal to Baffles' cellmate, Freddy the Forger, despite his obvious lack of similar credentials. At first reluctant to return to the outside world, Freddy agrees when he learns that the target is to be the Bank of the Potomac where his ex-wife deposits her alimony checks.
Once there, Freddy's skill with a pen proves useful after all - he injects ink from a fountain pen into the vault's timing mechanism which acts as a lubricant causing it to advance to a point equivalent to it's scheduled opening time freeing the trapped occupants.
Grateful for his newfound freedom, Freddy pledges that he has forged his last check, suggesting that he may take up safecracking instead - "it's a lot easier."