Zombie debts are old debts that have been resurrected, often by collection agencies. These are typically old debts. The statute of limitations may have expired on the debt. You may have paid the debt already. It may even belong to someone else. Any time a debt collector contacts you about a debt they must provide you with the details of the debt. You can dispute the debt. If you know your rights and assert them you can fight back against attempts to collect zombie debt.