Reviewing his 2005 album, "Passions," for The Washington Post, music critic Mike Joyce wrote that Mr. Hancock sang "in a highly personalized fashion, making comparisons moot. He phrases lyrics in strange, idiosyncratic ways at times and can leave listeners wondering if his vocal cords are capable of producing an echo. But he never sounds insincere or preoccupied with his influences."
Throughout the 1970s, Mr. Hancock sang and played bass with guitarist Gatton in Danny and the Fat Boys, a band whose diverse repertoire ranged from the dour laments of Leonard Cohen to the rockabilly of Carl Perkins.
Ignoring genre conventions, Gatton often mixed country, jazz and rock licks within the same song while Mr. Hancock sang as though the styles of Buddy Holly, Ray Charles and Fats Domino had all been mixed together in a musical blender. With Gatton on banjo, the trio — best known as a rock-and-roll unit — moonlighted as a bluegrass band with singer Liz Meyer.
The band's album "American Music" (1976) featured a mixture of doo-wop, rockabilly, country and even reggae songs, many from Mr. Hancock's pen. However, Gatton's frustration over the number of sidemen used on the recording led to the band's breakup.
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In 1978, Ripsaw, a Pennsylvania record label, approached Mr. Hancock about recording in the rockabilly style. Switching from bass to guitar, Mr. Hancock formed a new band, the Tennessee Rockets. His singles for the label, which included his signature song, "The Boogie Disease," followed the formula of Elvis Presley's early Sun records recordings — a hopped-up blues cover on one side paired with a bouncy country song on the flip side. Mr. Hancock also co-produced and accompanied the label's other rocker, Tex Rubinowitz.
"I was going to the same sources that Elvis Presley and Johnny Burnette went to, listening to folks like [country duo] the Delmore Brothers and [Delta bluesman] Arthur Crudup and finding material I could work with," he told The Post in 2001.
He lacked the marquee draw of other rockabilly acts, such as the Stray Cats and Robert Gordon, but Mr. Hancock's rockabilly recordings sold well in England, where his single "Rootie Tootie" went to No. 1 on the BBC rock-and-roll charts. With Rubinowitz and guitarist Evan Johns, he toured France at the height of the 1980s rockabilly revival.
"My music really is just rock 'n' roll," he told The Post in 1983, noting his disenchantment with the label "rockabilly." "It's no more rockabilly than NRBQ or Dave Edmunds, but if you do one rockabilly side on an album, you're a rockabilly band.
"And now if you have 'the look,' people will hear the music even if it isn't there," he added. "Everything the Stray Cats do isn't rockabilly, but some of the things Electric Light Orchestra does are."
His later, self-produced albums reflected a desire to avoid being pigeonholed. "On the Jazz" (2003), featured a mix of Dixieland, blues standards and Kansas City swing with an eight-piece jazz ensemble. "Out of the Darkness" (2008) found Mr. Hancock adapting his style to Southern soul.
Mr. Hancock also mentored and promoted other musicians. Working in the late 1970s with his brother Dale, Mr. Hancock produced the first albums by the Nighthawks and guitarist Tom Principato (with the band Powerhouse). He co-produced several oldies and doo-wop shows and coaxed his boyhood idol, boogie-woogie pianist Amos Milburn, out of retirement for an autumnal performance.
William Curtis Hancock Jr. was born in Alexandria, Va., on Nov. 4, 1946. His father was a railroad clerk. His mother worked at record stores and brought home 78s by rhythm-and-blues artists.
In high school, he formed a band, the Torquays, named for an instrumental hit by the Fireballs. After the group broke up, he took up bass guitar to increase his opportunities.
He went on the road with a garage rock band, Tito Mambo and the Disciples. However, the band's singer, whose act involved rising out of a coffin, was soon arrested in Rhode Island for hitting a drunk patron over the head with a microphone. The other musicians were left to fend for themselves, and Mr. Hancock decamped for Greenwich Village. There, he played banjo in a Dixieland band and passed the hat in folk clubs on his nights off.
When he returned to the Washington area, he sang and played bass in bands led by saxophonist Joe Stanley and guitarist Roy Buchanan and briefly studied classical guitar at the Peabody Conservatory in Baltimore.
In 1972, with Gatton and drummer Dave Elliott, he started the trio Fat Chance, initially as an outlet for his songwriting. They soon changed the name to Danny and the Fat Boys, and expanded to a quintet with saxophonist Ralph McDuffie and keyboardist Dick Heintze.
Survivors include his wife of 11 years, Carrie Slark of La Plata; and a brother.
Mr. Hancock told The Post that he first heard a rockabilly record on a jukebox in 1955, but he claimed he could not find out the name of the singer because he could not discern the label on the machine.
Seven years later, while listening to records and making out with a girlfriend, he heard the same song. "All of a sudden that record came on the phonograph," he recalled. "I jumped up so fast, I dumped her off my lap and right on the floor and said, 'What the hell is that?!'
"And she said, 'Dummy, that's Elvis Presley.' "
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