Sir James Peter Comyn (8 March 1921 – 5 January 1997) was an Irish-born barrister and English High Court judge.

The scion of a prominent Nationalist legal family, Comyn was sent to England after they fell out with Éamon de Valera.

Considered by many to be "the finest all-round advocate at the English bar",[1] Comyn was appointed to the High Court of Justice in 1978, serving on the bench until his retirement in 1985.

[1] Comyn spent six months as a trainee at The Irish Times under the editor R. M. Smyllie, but abandoned journalism after a joke he added to an obituary was printed in the paper, leading to his demotion to the racing department.

[4] In 1944, he began his pupillage with Edward Holroyd Pearce KC, later a law lord, and joined his chambers at Fountain Court.

[1] Comyn practised in London and on the Western circuit, supplementing his earnings by teaching banking, a subject of which he knew nothing.

[1] In 1975, he defeated the government's attempt to obtain an injunction against the publication of the diaries of former minister Richard Crossman (Attorney General v Jonathan Cape Ltd).