Casuarinaceae is a family of dicotyledonous flowering plants placed in the order Fagales, consisting of 3 or 4 genera and approximately 70 species of trees and shrubs native to the Old World tropics (Indo-Malaysia), Australia, and the Pacific islands. At one time, all of the species were placed in the genus Casuarina, but these are now split among Allocasuarina, Casuarina, Ceuthostoma, and Gymnostoma. In the Wettstein system, this family was the only one placed in the order Verticillatae. Likewise, in the Engler, Cronquist and Kubitzki systems, Casuarinaceae was the only family placed in the order Casuarinales.
Members of this family are characterized by drooping equisetoid (meaning "to look like Equisetum") twigs, are evergreen, and monoecious or dioecious. The roots have nitrogen-fixing nodules that contain the soil actinomycete Frankia.
The most widely used common name for Casuarinaceae species is sheoak or she-oak. Other common names include ironwood, bull-oak or buloke, and beefwood.