An anvil is a metalworking tool consisting of large block of metal (usually forged or cast steel), with a flattened top surface, upon which another object is struck (or "worked").

Anvils are as massive as they are practical, because the higher their inertia, the more efficiently they cause the energy of striking tools to be transferred to the work piece. On a quality anvil, the smith's hammer should rebound with almost as much energy as the smith puts into the downward stroke, ultimately making the smith's job easier and less physically strenuous. In most cases the anvil is used as a forging tool. Before the advent of modern welding technology, it was a primary tool of metal workers.

The great majority of modern anvils are made of cast or forged steel (the latter is stronger) that has been heat treated. Inexpensive anvils have been made of cast iron and low quality steel, but are considered unsuitable for serious use as they deform and lack rebound when struck.