William Primrose CBE (23 August 1904 – 1 May 1982) was a Scottish violist and teacher. He performed with the London String Quartet from 1930 to 1935. He then joined the NBC symphony orchestra where he formed the Primrose Quartet. He performed in various countries around the world as a soloist throughout his career. Primrose also taught at several universities and institutions. He is the author of several books on viola technique.

Primrose made his debut as a violin soloist in 1923; however his soloist career playing the viola didn't take off until 1941 when he started touring with Richard Crooks. He accompanied Crooks on five tours in the next four years, playing in 32 concerts in 1941-1942. While touring with Crooks, Arthur Judson, an influential concert manager, sought out Primrose. He signed with Judson who furthered Primrose's soloist career. Primrose doubled his concert performances, playing in 64 concerts in 1943–1944.

In 1944, he was the soloist in the first studio recording of Berlioz's Harold in Italy. That same year, he commissioned a viola concerto from Béla Bartók. This was left incomplete at Bartók's death in 1945, and had to wait four years for its completion by Tibor Serly. Primrose was the soloist in the world premiere performance of the concerto, on 2 December 1949. In 1950, Benjamin Britten wrote for him Lachrymae based on the song by Dowland.

Primrose was known for his tremendous technique. When he performed Paganini's violin caprices on viola, Mischa Elman is said to have exclaimed, "It must be easier on viola!" Primrose wrote many transcriptions and arrangements for viola, often technically dazzling, including "La Campanella" (from Paganini's second violin concerto) and the famous Nocturne from Borodin's second string quartet, the latter "out of jealousy" for the cello's long melodic lines.

He was made a Commander of the Order of the British Empire (CBE) by Queen Elizabeth II in 1953 in recognition of his musical contributions.