Isaac Hayes, the singer and songwriter whose luxurious, strutting Funk arrangements in songs like “Theme From ‘Shaft’ ” defined the glories and excesses of Soul music in the early 1970s, died on Sunday, August 10, in Memphis. He was 65. The Shelby County Sheriff’s Office said that Mr. Hayes’s wife, Adjowa, found him collapsed near a treadmill at their home in Cordova, an eastern suburb of Memphis, and he was pronounced dead an hour later. Mr. Hayes apparently died of a stroke, officials with the sheriff's department said Tuesday.

With his lascivious bass-baritone and flamboyant wardrobe, Mr. Hayes developed a musical persona that was an embodiment of the hyper-masculine, street-savvy characters of the so-called blaxploitation films of the era. In his theme song to Gordon Parks’s Shaft from 1971, the title character is summed up in a line that has become a classic of kitsch: “Who’s a black private dick/Who’s a sex machine to all the chicks?” (Furthermore: “He’s a complicated man/But no one understands him but his woman.”)

The Shaft theme won an Academy Award and has become one of his best-known songs. But Mr. Hayes’s career stretched far beyond soundtracks. For much of the 1960s and into the ’70s he was one of the principal songwriters and performers for Stax Records, the trailblazing Memphis R&B label, and in the 1990s he revived his career by providing the voice for the amorous and wise Chef on the cable television show South Park.

Isaac Hayes was born August 20, 1942, in a tin shack in rural Covington, Tennessee, to a mother who died early and a father who left home. He was raised largely by his grandparents, and worked in cotton fields while going to school. He began playing in local bands, and by early 1964, when he was 21, he was working as a backup musician for Stax. His first session was with Otis Redding.

Soon he began writing songs with David Porter, and their music — numbers like “Soul Man” and Hold On, I’m Comin’ ” for Sam and Dave, and “B-A-B-Y” for Carla Thomas — came to embody the Stax aesthetic. It was tight, catchy Pop, but full of sweat and grit, a proudly unpolished Southern alternative to Motown.

By the late 1960s Mr. Hayes was stepping out as a solo artist, and his reputation grew as much for his dress as for his music. The cover of his 1969 album, Hot Buttered Soul, pictured him in customary style: shaved head, dark shades, gold chains, bare chest. The album was similarly eccentric, consisting of just four songs, including lengthy, elaborate versions of Burt Bacharach and Hal David’s “Walk On By” and Jimmy Webb’s “By the Time I Get to Phoenix.” It also included spoken segments that he called “raps,” and the album became one of his biggest hits, reaching No. 8.

When he was approached to create the score to Shaft, one of the first blaxploitation films, Mr. Hayes said he also wanted the lead role. The part went to Richard Roundtree, but Mr. Hayes recorded the music anyway. It was done in four days with several members of the Bar-Kays, one of the house bands at Stax.

With a cymbal pattern borrowed from Redding’s “Try a Little Tenderness,” which Mr. Hayes had arranged, the song layered Funk guitars, horns, woodwinds, and strings, prefiguring disco. It became a No. 1 hit.

In 1971 he followed up the Shaft soundtrack with Black Moses, a double album that was another ambitious expansion of the vocabulary of Soul music. In its original issue, the cover folded out to reveal a portrait of Mr. Hayes in crucifix form.

In the mid-1970s Mr. Hayes’s finances collapsed and his music turned explicitly to disco, which turned out to be a career dead end. Through the 1970s and into the ’90s he acted in several films, including Escape From New York in 1981 and the spoof I’m Gonna Git You Sucka in 1988. His music from this era sold poorly, but his career revived in 1997 when he began playing Chef on South Park. A Scientologist, he quit the show in 2006, saying that he had been offended by an episode that ridiculed Tom Cruise and other prominent Scientologists. He also had a radio show in New York in the 1990s.

Mr. Hayes had health problems in recent years but had continued to tour and work occasionally in film (he had a role in Soul Men, a comedy set for release in November and starring Samuel L. Jackson and Bernie Mac, the comedian who died Saturday).

In an interview on Sunday The Associated Press, Mr. Porter, Mr. Hayes’s fellow songwriter, said that his friend was “recuperating from a stroke,” but added that “in the middle of all that he was still trying to have fun” and had even returned to his birthplace in Covington to go fishing.

Mr. Hayes had been married three times previously. In addition to his wife, he is survived by their son, Nana, and 11 other children.