Donnie Fritts, a songwriter, singer and piano player who helped shape both the soul music made in Muscle Shoals, Ala., in the 1960s and the outlaw country sensibility that bucked Nashville norms in the 1970s, died on Tuesday at a hospital in Birmingham, Ala. He was 76.

His death was confirmed by his friend and musical collaborator Andreas Werner, who said Mr. Fritts had been in declining health and had recently undergone heart surgery .

Though better known to enthusiasts of American roots music than to the general public — and probably better known as the pianist in Kris Kristofferson’s band than as a performer in his own right — Mr. Fritts was a creative force in Southern popular music for more than two decades .

As part of a close circle of songwriters working in Northern Alabama in the ’60s, he wrote or co-wrote signature songs for the likes of the soul singer Arthur Alexander (“Rainbow Road,” with Dan Penn) and the Box Tops (“Choo Choo Train,” with Eddie Hinton). “Choo Choo Train” is also featured on the soundtrack of Quentin Tarantino’s latest movie, “Once Upon a Time … in Hollywood.”