John David Souther, the Songwriters Hall of Fame inductee, musician and actor best known for penning hits for the Eagles, Linda Ronstadt, Roy Orbison, James Taylor and Don Henley, among others, died “peacefully in his New Mexico home” on Tuesday, 9/17, according to a statement. He was 78. No cause of death was given.

Less venerated than a number of his fellow leading lights of the 1970s SoCal golden age but hailed by his friend and management client Irving Azoff as “an American treasure,” Souther penned memorable songs sung by his higher-profile contemporaries. During his longtime partnership with Frey, Souther co-wrote the Eagles songs “Best of My Love,” “James Dean,” “New Kid in Town” and “Doolin-Dalton,” as well as “Heartache Tonight” with Bob Seger, Frey and Henley.

Souther’s many collaborations through the years also included several songs for his onetime girlfriend Ronstadt, including “Faithless Love” and “White Rhythm and Blues.” They dueted on “Prisoner in Disguise,” “Sometimes You Can’t Win” and “Hearts Against the Wind,” the latter featured on the soundtrack to 1980’s Urban Cowboy.

During his on-and-off solo career, he scored a hit in 1979 with “You’re Only Lonely” after forming The Souther-Hillman-Furay Band with former Byrds member Chris Hillman and Poco’s Richie Furay.

As an actor, Souther starred in shows like Nashville, Thirtysomething and Purgatory, as well as the films Postcards From the Edge, My Girl 2 and Deadline.

Born in Detroit but raised in Amarillo, Texas, Souther formed Longbranch Pennywhistle in the late ’60s with fellow Detroit native Frey after they met in L.A. As regulars at the Troubadour bar, ground zero for the nascent country-rock movement. Souther, Frey, Henley and Ronstadt formed close relationships, leading to Frey and Henley playing in Ronstadt’s band, Souther and Frey signing with David Geffen and Elliot Roberts’ management company and Frey and Henley forming the Eagles.

Early on, they pondered making Souther a member of their new band. “It was about three or four months into the band’s life, when we were all officially part of the Geffen-Roberts hang,” original Eagle Bernie Leadon recalled to author Barney Hoskyns. “It was probably based on the fact that JD could write and was another good-looking guy. But then it was, like, ‘Well, what’s he gonna play? We don’t need another guitar player.’”

When Geffen left Roberts in 1971 to start his Asylum label, his first signings were, the Eagles, Souther and Ned Doheny. “David took the crème de la crème from that scene and signed them on the basis of their cuteness,” scene chronicler Eve Babitz once quipped. Although Souther and Doheny didn’t break through as solo artists, JD became a core contributor to the Eagles’ success and gained the respect of his peers.

“The guys in the South that were our age, like Henley and Souther, were not playing folk music,” artist Chris Darrow noted to Hoskyns. “The melodic structures for their ballads came directly from Memphis and Muscle Shoals. All those songs that JD Souther wrote or co-wrote, that’s where they came from. And all those guys wanted to be JD.”