Baron Frédéric Alfred d'Erlanger (29 May 1868 in Paris – 23 April 1943 in London) was an Anglo-French composer, banker and patron of the arts. His father, Baron Frederic Emile d'Erlanger, was a German, while his mother, Mathilde (née Slidell), was an American. One of four sons, his father was the head of a French banking house. He began his musical studies in Paris under Anselm Ehmant, his only teacher. His first work, a book of songs, was published when d'Erlanger was 20 years of age. Shortly afterwards, in 1886, he moved to London with his elder brother, Emile d'Erlanger, to work as a banker, for the private banking firm that his father owned. Both d'Erlanger and his brother became naturalised Englishmen. His compositions include works of all kinds, notably the operas Jehan de Saintré (Aix-les-Bains, 1 Aug. 1893; Hamburg, 1894), Inès Menso (produced, under the pseudonym of Ferd. Regnal, in London at Covent Garden on 10 July 1897, and subsequently in Germany); Tess (after Thomas Hardy's 'Tess of the d'Urbervilles'), produced at the San Carlo Theatre, Naples, on 7 April 1906 and at Covent Garden on 14 July 1909, on both occasions under the baton of Ettore Panizza; and Noël, produced at the Paris Opéra-Comique on 28 December 1910.
In 1935 his ballet Les Cents Baisers, with a libretto by Boris Kochno, was produced by the Ballets Russes, choreographed by Bronislava Nijinska, with decor and costumes by Jean Hugo. His other works included a string Quartet, a Sonata for violin and pianoforte, an Andante symphonique for cello and orchestra, a Quintet for pianoforte and strings, a Suite symphonique for orchestra (1895), a violin Concerto, Op. 17 played by Kreisler at the Philharmonic Concert of 12 March 1903, and a Concerto symphonique for piano and orchestra (1921). One of his later works was a Requiem for solo voices, chorus and orchestra in 1931. Clearness of form and elegance of idea and expression are the distinguishing marks of d'Erlanger's music, whether in his operatic work, in his chamber and orchestral music, or in his songs.
A millionaire, d'Erlanger was described as a "genuine Renaissance man"; he was a noted patron of the arts in London and invested in developing countries, financing department store chains in South America and railways in South Africa.
D'Erlanger was a founding member of the Oxford & Cambridge Musical Club. "Baron Fred," as he was known, was a frequent participant in the regular Thursday musical soirées of the Club.
In 1925, d'Erlanger married Catherine, "a French woman of good family".