A form of guaranty used in a leasing context. Usually a good guy guaranty is delivered by the tenant's parent or principal. As the guarantor, the tenant's parent or its principal assumes the tenant's payment and performance obligations under the lease by agreeing to compensate the landlord in the event of the tenant's default.

A good guy guaranty differs from a regular lease guaranty because the obligations of the guarantor under the good guy guaranty cease once the tenant has vacated the leased premises. The good guy guaranty provides the landlord with extra leverage to ensure that a defaulting tenant vacates the leased premises in an expedited manner.