An American country rock bass guitarist. He was a member of the International Submarine Band (ISB) and the Flying Burrito Brothers and co-wrote several songs with Gram Parsons.

Born in Meridian, Mississippi, he began playing in local bands in the South before moving to California at the age of 17. He played with Joel Scott Hill before joining Gram Parsons in the ISB. He played with Parsons after the end of the ISB and again after Parsons left the Byrds, before co-founding the Flying Burrito Brothers with him. He played bass and piano on The Gilded Palace of Sin, but left before Burrito Deluxe. When Parsons left the Burritos, Ethridge played with him again, touring with Byron Berline, Emmylou Harris, Clarence White, Gene Parsons, Sneaky Pete Kleinow and Roland White. After Parsons' death, Ethridge played in 1974 with the Docker Hill Boys, an informal group which included Gene Parsons and Joel Scott Hill. These three controversially reformed the Burritos in 1975 with Kleinow and Gib Guilbeau, recording Flying Again.

Ethridge left the Burritos again in February 1976, returning to session work. He has been a session musician throughout his career, recording with many leading country-tinged acts, including Judy Collins, Johnny Winter, Ry Cooder, Leon Russell, Randy Newman, Linda Ronstadt, the Byrds and Jackson Browne. He also toured with Willie Nelson's band for almost 8 years.