Furneaux Cook (1839 – 19 January 1903), born John Furneaux Cook, was an English opera singer and actor best known for baritone roles in the comic operas of Gilbert and Sullivan and Alfred Cellier on the London stage. Cook appeared on stage for over 30 years in London, the British provinces and America.
Cook was the brother of opera singer T. Aynsley Cook (1832–1894) and fellow Savoyard Alice Aynsley Cook (1849–1938).
One of Cook's earliest professional engagements was in the obscure Michael Balfe opera, Letty the Basketmaker, produced by John Hollingshead at the Gaiety Theatre in London in 1868. This was played as part of the same programme with W. S. Gilbert's burlesque Robert the Devil. Cook also played Peter the Watchman in the burlesque Cinderella the Younger (by Alfred Thompson, composed by Émile Jonas) at the Gaiety in 1871, and the title character in The Sultan of Mocha, by Alfred Cellier, in Manchester in 1874–75.
Cook then joined one of Richard D'Oyly Carte's touring companies in 1878 in Gilbert and Sullivan's The Sorcerer, playing the vicar, Doctor Daly, and also Old Matthew in the curtain-raiser Breaking the Spell, by H. B. Farnie, based on Jacques Offenbach's Le Violoneau. From 1879 to 1880, he travelled to America with Gilbert, Sullivan and the D'Oyly Carte Opera Company to present the authorised version of H.M.S. Pinafore, in which he played Dick Deadeye, and The Pirates of Penzance, in which he created the role of Samuel first in New York and then in Philadelphia, where he moved up to the larger roles of Sergeant of Police in Pirates and Captain Corcoran in Pinafore. He also played Dr. Daly on this tour. On 23 April 1880, the company gave a benefit for Cook consisting of Pinafore and the second act of Pirates, in which Cook played Deadeye, Corcoran (apparently one in each act), and the Sergeant.