Debtor

In legal terms, any individual or company that owes money is referred to as a "debtor."

The money owed can be a result of unpaid loan, it could be from taxes, it could be from adjudication awards, or from a number of other scenarios.

Debtor usually only refers to someone who owes money. When John Wick went after the Russian Mob for killing his dog, they were not debtors, though they wound up paying more than money at the end.