James Isaac Moore (January 11, 1924 – January 31, 1970), better known by his stage name Slim Harpo, was an American blues musician, a leading exponent of the swamp blues style, and “one of the most commercially successful blues artists of his day”. His most successful and influential recordings included “I’m a King Bee” (1957), “Rainin’ in My Heart” (1961), and “Baby Scratch My Back” (1966) which reached no. 1 on the R&B chart and no.16 on the US pop chart. A master of the blues harmonica, his stage name was derived from the popular nickname for that instrument, the “harp”.

Moore was born in Lobdell, Louisiana, the eldest child in his family. After his parents died he worked as a longshoreman and construction worker in New Orleans in the late 1930s and early 1940s. Influenced in style by Jimmy Reed, he began performing in Baton Rouge bars under the name Harmonica Slim, and also accompanied his brother-in-law Lightnin’ Slim in live performances. He started his own recording career in March 1957, working with the A&R man and record producer J. D. “Jay” Miller in Crowley, Louisiana. At his wife’s suggestion, he took the name Slim Harpo in order to differentiate himself from another performer called Harmonica Slim. His first solo release, for Excello Records, based in Nashville, Tennessee, was “I’m a King Bee“, backed with “I Got Love If You Want It” in 1957. The other musicians on the recording were Gabriel “Guitar Gable” Perrodin (guitar), John “Fats” Perrodin (bass), and Clarence “Jockey” Etienne (drums). Harpo played guitar in his live shows, but he usually used other guitarists when recording. The record was a regional hit but failed to make the national charts. He followed up with several more singles for Excello before having his first chart hit, “Rainin’ in My Heart”, in early 1961. The record reached number 17 on the Billboard R&B chart and number 34 on the U.S. pop chart, and it was followed soon after with an LP of the same name and additional singles. Many of his songs were co-written with his wife, Lovelle Moore, although she never received credit.

Never a full-time musician, Harpo had his own trucking business during the 1960s. According to writer Ryan Whirty, “Harpo and his band needed to tour constantly and play as much as possible; times were frequently lean financially, and the men had to scrape up whatever they could get.” But, by 1964, several of his tracks had been released on albums and singles in the UK, and British rock bands like the Rolling Stones, the Pretty Things, the Yardbirds, the Kinks, Pink Floyd and Them began to feature versions of his songs in their early repertoires. The Moody Bluesreportedly took their name from an instrumental track of Slim’s called “Moody Blues”.