In the United States, a third-party administrator is an organization that processes insurance claims or certain aspects of employee benefit plans for a separate entity.

A third-party beneficiary, in the law of contracts, is a person who may have the right to sue on a contract, despite not having originally been an active party to the contract.

(law) A derivative lawsuit brought by a defendant in an original lawsuit, claiming that another new party being brought in is responsible for or should share in the plaintiff's damages against the defendant.

(abbreviated as 3PL, or TPL) an organization's long term commitment of outsourcing its distribution services to third-party logistics businesses.