Abstract: Several embodiments of reactive biasing fasteners are described. The fasteners are utilized in place of jam nuts and Belleville washers providing for the storage of a pre-load and effectively providing a locking function to prevent unintended loosening of an associated bolt. The embodiments resiliently deform under load to store pre-load or live load energy. Further, the fasteners provide a means for interfacing with a self-reacting tightening power tool thereby eliminating or minimizing the need for reaction arms. Additionally, several embodiments through the incorporation of a threaded bore effectively act to create a substantially torsionless live load on the portion of a bolt located in the bolt hole of a workpiece when in use. The resilient deformation of the biasing fasteners permits the live load to be stored therein and accordingly lessens the risk of loosening of the bolted joint due to exteriorly applied forces such as but not limited to vibration and thermal expansion and contraction.