A person who offers loans at extremely high interest rates, usually not registered with the National Credit Regulators and thus illegally granting credit, is a loan shark.
Typically offering insane payback amounts and periods, as well as incredibly high interest rates, these creditors use predatory lending practices to take advantage of those who have no other choice. With a mafia movie debt collection style and a shady business, these are not official creditors and are not the types of people you want to owe money to.
Registered creditor providers will always have to abide by certain guidelines or risk repercussions, operating within the law they are held to certain standards that the dis-honorable loan sharks can ignore and circumvent.