Gray cast iron is a type of cast iron with lamellar graphite. It got its name from the gray color of the fracture, which is the result of the presence of graphite in the microstructure.

It is used for housings where the stiffness of the component is more important than its tensile strength, such as internal combustion engine cylinder blocks, pump housings, valve bodies, electrical boxes and decorative castings. The high thermal conductivity and specific heat capacity of gray cast iron are often used to make cookware and disc brake rotors.