Henry Clay Work (October 1, 1832, Middletown – June 8, 1884, Hartford) was an American songwriter and composer. He is best remembered for his musical contributions to the Union in the Civil War—songs documenting the afflictions of slavery, the hardships of army life, and Northern triumphs in the conflict. Besides patriotic pieces, he composed sentimental ballads, some of which promoted the growing temperance movement. Many of Work's compositions were performed at minstrel shows and Civil War veteran reunions. Although largely forgotten nowadays, he was one of the most successful musicians of his time, comparable to Stephen Foster and George F. Root in sales and sheer influence.

Work's father, Alanson, was an abolitionist who strove to free fugitive slaves. While a youth, Henry initiated a career in printing, one that lasted his entire life. Although lacking formal music training, his passion for song manifested itself early on as he wrote poems for newspapers. Work first published a complete musical piece in 1853, whose moderate success drove him to pursue songwriting further. His career came of age at the Civil War's outbreak; Work collaborated with the Chicagoan publishing firm Root & Cady to compose 27 pro-Union tunes, some of which, such as "Kingdom Coming" (1862) and "Marching Through Georgia" (1865) proved among the most popular of the war. After the war, Work ventured in balladry, but familial and financial woes would demotivate him considerably, worsened by Root & Cady's closure in 1871. He quit songwriting altogether for a few years. After agreeing to collaborate with Chauncey M. Cady in 1876, his output briefly resurged, yielding one sole major hit, "Grandfather's Clock" (1876). Nonetheless, Work could not reproduce his wartime fame and fortune, and he died virtually forgotten aged 51.

As a songwriter, Work is renowned for his perceived dexterity in African-American dialect, seriocomedy, and melody.