| Honorific Prefix: | Rear Admiral |
| Merddyn Ray Terry-Lloyd | |
| Birth Date: | 1913 7, df=yes |
| Birth Place: | Queenstown, Eastern Cape, Cape Province, Union of South Africa |
| Death Place: | Pretoria, Transvaal, South Africa |
| Rank: | Rear Admiral |
| Commands: | |
Rear Admiral Merddyn Ray Terry-Lloyd (29 July 1913, Queenstown28 October 1978, Pretoria) was a South African naval officer.
He attended Queen's College in Queenstown before moving to finish his schooling at St. Andrew's College, Grahamstown. After leaving school in 1930 he went to work at the Netherlands Bank in East London.
He had wanted to join the Royal Navy at the age of 12 as a cadet but his father forbade it. Still intent on joining the Navy he joined the South African Division of the Royal Naval Volunteer Reserve in 1931. He was commissioned as a Sub Lieutenant in 1934, and promoted to Lieutenant in 1938.
In 1940, he transferred to the Seaward Defence Force, the naval component of the South African Active Citizen Force and attended Anti Submarine courses before being given command of . In 1942 he was stationed in the Mediterranean and commanded and . He was promoted Lieutenant Commander in 1943 and appointed Senior Officer Anti Submarine Flotillas in 1944, followed by a post as Staff Officer in Cape Town and General Staff Officer in Pretoria in 1945.
In 1946, he was appointed to the South African Permanent Force and sent to England on a Staff course followed by a stint as a liaison officer at the South African High Commission. On his arrival in South Africa he was given command of followed by command of in November 1948. He served as Staff Officer in Pretoria from 1950 until January 1954 when he assumed command of .
In August 1955, he was appointed Officer Commanding of the Naval base at Salisbury Island before being sent to England in 1956 to take command of the frigate . On his promotion to Captain he was also appointed as known as F10.
He was then sent to England to oversee the construction of the Type 12 frigates purchased under the Simonstown Agreement, also serving as the first captain of . On the ships arrival in Simon's Town in 1963 he was promoted to Commodore.
On 1 February 1965 he was appointed to Headquarters as Director Operations, a position he held until 1 July 1966, when he was appointed Chief of Naval Staff in the rank of Rear Admiral
His final posting before his retirement in 1973 was as Armed Forces attache at the South African Embassy in London. Shortly before his retirement he was invested with the Star of South Africa
He died on 28 October 1978.