Otis Verries Hicks, known as Lightnin' Slim (March 13, 1913 – July 27, 1974), was an African-American Louisiana blues musician, who recorded for Excello Records and played in a style similar to its other Louisiana artists. The blues critic ED Denson ranked him as one of the five great bluesmen of the 1950s, along with Muddy Waters, Little Walter, Howlin' Wolf and Sonny Boy Williamson.

Given his recorded output, it's highly doubtful that
either his father or brother knew how to play in any key other than E natural,
as Lightnin' used the same patterns over and over on his recordings, only
changing keys when he used a capo or had his guitar detuned a full step. But
the rudiments were all he needed, and by the late '30s/early '40s he was a
mainstay of the local picnic/country supper circuit around St. Francisville.
In
1946 he moved to Baton Rouge, playing on weekends in local ghetto bars, and
started to make a name for himself on the local circuit, first working as a
member of Big Poppa's band, then on his own.

His first recording was "Bad Luck Blues"
("If it wasn't for bad luck, I wouldn't have no luck at all"),
released by J. D. "Jay" Miller's Feature Records in 1954. It was
Miller, who had a penchant for picking colourful artists' names, who christened
him "Lightnin' Slim".
The acknowledged kingpin of the Louisiana school of
blues, Lightnin' Slim built his style on his grainy but expressive vocals and
rudimentary guitar work, with usually nothing more than a harmonica and a
drummer in support. It was down-home country blues edged two steps further into
the mainstream, first by virtue of his electric guitar, and second by the sound
of the local Crowley, LA musicians who backed him being bathed in simmering,
pulsating tape echo.
As the first great star of producer J.D. Miller's blues
talent stable, Lightnin' Slim had a successful formula that scored regional
hits on the Nashville-based Excello label for over a decade, with one of them,
"Rooster Blues," making the national R&B charts in 1959.
Combining the country ambience of a Lightnin' Hopkins with the plodding
insistence of a Muddy Waters, Lightnin' Slim's music belonged uniquely to him,
the perfect blues raconteur, even when he was reshaping others' material to his
dark, somber style.

He also possessed one of the truly great blues voices,
unadorned and unaffected, making the world-weariness of a Sonny Boy Williamson
sound like the second coming of Good Time Charlie by comparison. His
exhortation to "blow your harmonica, son" has become one of the
great, mournful catch phrases of the blues, and even on his most rockin'
numbers, there's a sense that you are listening less to an uptempo offering
than a slow blues just being played faster. Lightnin' always sounded like bad
luck just moved into his home approximately an hour after his mother-in-law
did.
Slim stopped performing the blues for a time and
eventually worked in a foundry in Pontiac, Michigan, as a result of which his
hands were constantly exposed to high temperatures. He was rediscovered by Fred
Reif in 1970, in Pontiac, where he was living in a rented room at Slim Harpo's
sister's house. Reif soon got him back performing again and a new recording
contract with Excello, this time through Bud Howell, then the president of the
company. His first engagement was a reunion concert in 1971 at the University
of Chicago Folk Festival with Lazy Lester, whom Reif had brought from Baton
Rouge in January of that year.

In July 1974, Slim died of stomach cancer in Detroit,
Michigan, aged 61.
(Edited from Wikipedia & AllMusic)