Singers Scott Walker and Lulu hold a clutch of music awards in 1968. Mr. Walker was a baritone-voiced crooner turned avant-garde composer. (Ballard/Express/Getty Images)

Scott Walker, a singer-songwriter who became a 1960s pop sensation as the leader of the Walker Brothers, then turned toward dark and moody avant-garde compositions as a solo artist, died March 22 in London. He was 76.

His record company, 4AD, announced the death but did not say precisely where or how he died.

Mr. Walker was a session bassist before he rose to fame with the Walker Brothers, an easy-listening pop trio that topped the charts in Britain and reached the Top 40 in the United States. Their 1960s hits included “Make It Easy on Yourself,” written by Burt Bacharach and Hal David, and “The Sun Ain’t Gonna Shine Anymore,” by Bob Crewe and Bob Gaudio.

Although the group was based in England, Mr. Walker and his bandmates, who went by John Walker and Gary Walker, were American. They were also neither siblings nor Walkers, a last name they adopted around the time they moved to Britain in 1965.

Mr. Walker struck out on his own in 1967, releasing the first of four solo albums in three years, all titled “Scott.” Thickly orchestrated and often haunting, the records initially featured covers of songs by Jacques Brel, the Belgian chanteur, before comprising originals by the baritone-voiced Mr. Walker.

His fourth album, “Scott 4” (1969), sold relatively few copies but has since acquired the status of a cult classic, combining lyrics about “the neo-Stalinist regime” and Ingmar Bergman’s film “The Seventh Seal” with arrangements that echoed the soundtracks of Western film composer Ennio Morricone.

Mr. Walker shot to fame in the 1960s as the singer of Walker Brothers hits including “The Sun Ain’t Gonna Shine Anymore.” (David Redfern/Getty Images)

Mr. Walker was cited as an influence by musicians including Thom Yorke of Radiohead, Jarvis Cocker of Pulp, and David Bowie, who served as executive producer of the 2006 documentary “Scott Walker: 30 Century Man.”

Noel Scott Engel was born in Hamilton, Ohio, on Jan. 9, 1943. He changed his name after joining the Walker Brothers, which reunited for several albums in the late 1970s.

Mr. Walker later worked as a producer of songs and movie scores, and released solo records such as “Climate of Hunter” (1984), “Tilt” (1995) and “Bish Bosch” (2012).

“Walker’s latter-day albums are fearless and violent, featuring wailing donkeys, moans, scrapes, and famously, the sound of someone punching meat,” Pitchfork reviewer Mike Powell wrote in 2013. “They seem to have been written in another language entirely.”

Survivors include his partner, Beverly; a daughter, Lee; and a granddaughter, according to 4AD.