The Udaloy class, Soviet designation Project 1155 Fregat and Russian designation Project 11551 Fregat-M, are series of anti-submarine guided-missile destroyers built for the Soviet Navy, seven of which are currently in service with the Russian Navy. Twelve ships were built between 1980 and 1990, while the thirteenth ship built to a modified design, known as Udaloy II class, followed in 1999. They complement the Sovremenny-class destroyers in anti-aircraft and anti-surface warfare operations. The codename Udaloy comes from an archaic Russian adjective удалой, meaning daring or bold.

A guided-missile destroyer (DDG) is a destroyer whose primary armament is guided missiles so they can provide anti-aircraft warfare screening for the fleet. The NATO standard designation for these vessels is DDG, while destroyers which have a primary gun armament or a small number of anti-aircraft missiles sufficient only for point-defense are designated DD. Nations vary in their use of destroyer D designation in their hull pennant numbering, either prefixing or dropping it altogether.