Loan shark

A loan shark is a person that sells loans with very high interest rates. People go to loan sharks for many reasons. It is often because no one else will lend them money. Loan sharks tend to ask for something beforehand, like someone's passport. Loan sharks are often illegal.
Loan sharks are called 'loan sharks' because they are like sharks; aggressive, angry, and greedy. They can do many illegal things to just get repayment, like kidnapping or even killing.