The Type 23 frigate or Duke-class is a class of frigate built for the United Kingdom's Royal Navy. The ships are named after British Dukes, thus leading to the class being commonly known as the Duke-class. The first Type 23 was commissioned in 1989, and the sixteenth, HMS St Albans was commissioned in June 2002. They form the core of the Royal Navy's destroyer and frigate fleet and serve alongside the Type 45 destroyers. Originally designed for anti-submarine warfare in the North Atlantic, the Royal Navy’s Type 23 frigates have proven their versatility in warfighting, peace-keeping and maritime security operations around the globe. Thirteen Type 23 frigates remain in service with the Royal Navy, with three vessels having been sold to Chile and handed over to the Chilean Navy.

The Royal Navy’s current Type 23 frigates will be replaced by the Global Combat Ship starting from 2021.As of 2012 it is planned that HMS Argyll will be the first Type 23 to retire from the Royal Navy in 2023 while HMS St Albans will be the last, in 2036.

Type 23 may refer to: