Eyvind Alnæs (29 April 1872, Fredrikstad – 24 December 1932, Oslo) was a Norwegian composer, pianist, organist and choir director.
Alnæs was born in Fredrikstad, as the son of headmaster Johannes Jørgen Lauritz Alnæs and Elise Martine Hansen. He married Emilie Thorne in 1903. He was the father of Lise Børsum, and grandfather of Finn Alnæs.
Alnæs studied music first in Oslo with Iver Holter, then in Leipzig with Carl Reinecke and, after the première of his first symphony in 1896, in Berlin with Julius Ruthardt.
From 1895 to 1907 Alnæs served as an organist in Drammen, and then for many years played the organ in several churches and conducted choirs in Oslo. He helped found the Norwegian Society of Composers.
Alnæs wrote music in a late Romantic style; his output included two symphonies, one set of symphonic variations, a piano concerto, pieces for piano, chorale preludes for organ, choral works, and art songs (in Norwegian, romanser).
A number of songs by Alnæs have been recorded by the likes of Kirsten Flagstad and Feodor Chaliapin. In 2007 the first recording of Alnæs's Piano Concerto in D major, Op. 27 (published c. 1919) was released; it featured Piers Lane as the piano soloist and the Bergen Philharmonic Orchestra conducted by Andrew Litton. In early 2010 the premiere recording of his two symphonies - no.1 in C minor, Op.7 and no.2 in D major, Op.43 - was released, with the Latvian National Symphony Orchestra conducted by Terje Mikkelsen.