Otis Blue/Otis Redding Sings Soul (often referred to simply as Otis Blue) is the third studio album by American soul singer and songwriter Otis Redding. It was first released on September 15, 1965, as an LP record through the Stax Records subsidiary label Volt.

Otis Blue is composed mainly of cover versions of contemporary R&B hits, exploring themes from the blues and love ballads, among others. Three of the LP's eleven songs were written by Redding, and three others were written by fellow soul singer Sam Cooke, who had died several months before the album was made. Except for one track, Otis Blue was recorded in the span of 24 hours from July 9 to 10, 1965, at the Stax recording studio in Memphis, Tennessee. As with Redding's previous records, he was backed by the Stax house band Booker T. & the M.G.'s, a horn section featuring members of the Mar-Keys and the Memphis Horns, and pianist Isaac Hayes, providing a rhythmic Southern soul accompaniment for the singer's exuberant and forceful performances.

Otis Blue was a crossover success for Redding and proved one of his best-selling LPs with more than 250,000 copies sold. It was his first to top the US R&B LPs chart and also reached number 6 on the UK Albums Chart, while three of its singles became top 40 hits: the Redding original "I've Been Loving You Too Long", the Rolling Stones cover "Satisfaction", and "Respect" (later repopularized by Aretha Franklin). Released at the beginning of the album era, Otis Blue is considered by critics to be Redding's first fully realized LP and the definitive soul album of its period. It ranks frequently and highly on professional listings of the best albums, including Rolling Stone magazine's "500 Greatest Albums of All Time" (at number 78) and Time magazine's "All-Time 100 Greatest Albums" (at number 92). A two-disc collector's edition of Otis Blue was released in 2008 by Rhino Records.