What value of the bond that is paid back at maturity is known as?

The value of the bond that is paid back at maturity is known as the "face value" or "par value." This is the amount that the issuer agrees to pay the bondholder when the bond matures, not including any interest payments made during the life of the bond. The face value is typically set at $1,000 for corporate bonds, but it can vary depending on the bond's terms.