GCHQ Bude, also known as GCHQ Composite Signals Organisation Station Morwenstow, abbreviated to GCHQ CSO Morwenstow, is a UK Government satellite ground station and eavesdropping centre located on the north Cornwall coast at Cleave Camp, between the small villages of Morwenstow and Coombe. It is operated by the British signals intelligence service, officially known as the Government Communications Headquarters, commonly abbreviated GCHQ. It is located on part of the site of the former World War II airfield, RAF Cleave.

The site of GCHQ Bude is in Morwenstow, the northernmost parish of Cornwall. During World War II, the location was developed for and used by the Royal Air Force (RAF). RAF Cleave was conceived as housing target and target support aircraft for firing ranges along the north Cornwall coast, and land was acquired from Cleave Manor. In 1939, it became home to two flights of 1 Anti-Aircraft Co-operation Unit (1AAC). In 1943, No. 639 Squadron was established on the site for the remainder of the war. The airfield was put under maintenance in April 1945, staying under government ownership.

In the early 1960s, developments occurred which appear to have prompted the establishment of the facility now known as GCHQ Bude. In 1962, a satellite receiving station for the commercial communication satellites of Intelsat was established at Goonhilly Downs, just over 60 miles (100 kilometres) south-southwest of Morwenstow.

The downstream link from the Intelsat satellites could easily be intercepted by placing receiver dishes nearby in the satellites' 'footprint'. For that, the land at Cleave was allotted to the Ministry of Public Building and Works in 1967, and construction of the satellite interception station began in 1969. Two 27 m (90 ft) dishes appeared first, followed by smaller dishes in the ensuing years. The station was originally signposted as 'CSOS Morwenstow', with 'CSOS' standing for Composite Signals Organisation Station. In 2001, a third large dish appeared, and the station eventually became known as 'GCHQ Bude'.

From its inception, the station has been an Anglo-American co-operative project. The United States National Security Agency (NSA) paid for most of the infrastructure and the technology. The running costs, like payments for the staff, were paid by GCHQ, who also provided the land. The intelligence that was collected by the Bude satellite station was shared between NSA and GCHQ, and was jointly processed.

Another sign of the close cooperation between both countries was that Sir Leonard Hooper, GCHQ director in the late 1960s, wrote to his NSA counterpart regarding the then two large dishes. He suggested naming them 'Pat' and 'Louis', after NSA director Marshall 'Pat' Carter and his deputy, Louis Tordella.

In 2010, the National Security Agency paid GCHQ £15.5m for redevelopments at the site.

In 1963, TAT-3, an undersea cable linking the United Kingdom to the United States, was laid from Tuckerton, New Jersey, US to Widemouth Bay, Cornwall, just 10 km (6 mi) south of the site at Cleave Camp. The British General Post Office (GPO) routinely monitored all communications passing along the TAT-3 cable, forwarding any messages they felt were relevant to the security services.