The fibula free flap is a versatile workhorse flap for bony reconstructions of the mandible, maxilla, long bones, spine, and pelvis. It has many anatomic advantages including a long vascular pedicle, reliable anatomy, and a long linear bone shape that can be carved into a variety of orientations. The primary vascular supply to the flap is the peroneal artery and its paired venae comitantes which runs along the deep surface of the interosseous membrane between the tibia and fibula. Dissection of the flap can be done rapidly and enables a two-team approach for complex multispecialty ablative/reconstructive procedures. There are multiple perforators to the skin surface which allow for skin paddles of varying geometry and also the potential for a chimeric flap configuration in more complicated reconstructions. The donor site is well tolerated and most patients will return to normal ambulation. In this chapter we describe the anatomy of the flap and the procedural steps to flap elevation. Several commonly used applications are reviewed including mandible, maxilla, long bone, and spine. Case examples are also presented depicting the applications of the flap in varying clinical scenarios.