With its riveting orchestration, definitive guitar play and signature sensual baritone vocals, Isaac Hayes’ theme song for the 1971 movie “Shaft” not only became one of pop music’s iconic songs, but also the defining work of Hayes’ career.

Yet the “Theme from Shaft,” which would earn both Grammys and an Oscar, was just a snippet of the groundbreaking music for which Hayes — who died Sunday at age 65 — was responsible.

He penned soul classics like “Hold On I’m Comin'” for Sam & Dave, helped usher in the era of disco and was a goldmine for countless hip-hop and R&B artists who used his illustrious arrangements as the focal point for their songs decades later.

“Isaac Hayes embodies everything that’s soul music,” Collin Stanback, an A&R executive at Stax, told The Associated Press on Sunday. “When you think of soul music you think of Isaac Hayes — the expression … the sound and the creativity that goes along with it.”

His influence also extended beyond music. His trademarked bald head, full beard and muscular frame, often adorned with a multitude of gold chains, made him a fashion trendsetter at a time when most of his contemporaries were sporting blowout Afros. He was also a symbol of black pride, and an activist for civil rights.

The Rev. Al Sharpton called Hayes a “creative genius” and added, “even in his later years he never hesitated to appear for a cause or endorse something that he felt was for the good of mankind. He will be sorely missed.”

Hayes also acted in movies including “Tough Guys,” ”I’m Gonna Get You Sucka” and “Hustle & Flow.” He had recently completed the movie “Soul Men,” in which he played himself; the film also starred Samuel Jackson and Bernie Mac, who died on Saturday after a bout with pneumonia. And a new generation of fans discovered the man behind “Shaft” when, in 1997, he became the voice of Chef on the Comedy Central show “South Park.”

Hayes, a member of the Rock and Roll Hall of Fame, was pronounced dead at Baptist Memorial Hospital-Memphis in Memphis, Tenn., after collapsing Sunday afternoon near a treadmill in his home nearby.

Steve Shular, a spokesman for the sheriff’s office, said authorities received a 911 call after Hayes’ wife and young son and his wife’s cousin returned home from the grocery store and found him collapsed in a downstairs bedroom. A sheriff’s deputy administered CPR until paramedics arrived.

Stanback said he was shocked to learn of the death of the singer, who was about to start work on a new record for Stax, the label Hayes helped make legendary.

In an industry filled with colorful and dynamic figures, Hayes was a standout on several levels, from his smooth baritone to his flamboyant style: It was almost as if he was made to be a musical god.

But Hayes spent the early part of his career firmly in the musical background. A self-taught musician from Covington, Tenn., he made a name for himself playing with various bands around Memphis. In 1964, he was hired by Stax Records to be a backup pianist, working as a session musician for Otis Redding and others. He also played saxophone.

He began writing songs, establishing a songwriting partnership with David Porter, and in the 1960s they wrote classic hits for Sam and Dave such as “Hold On, I’m Coming,” ”Soul Man,” and “When Something is Wrong With My Baby.” They also wrote for other Stax artists including Carla Thomas.

Hayes’ work as a composer helped him secure a deal as a solo artist. His first album, “Presenting Isaac Hayes,” was a poor seller, the result of an impromptu jam session. But after getting creative control, he delivered his next album, “Hot Buttered Soul” in 1969, and it made him a star.

Hayes offered something completely different to the musical world. In an era of straightened hair or Afros, Hayes was bald: “His look was just so profound,” Stanback said. “He was like a superhero.”

Whereas other soul crooners showed their passion through wails, Hayes delivery was calm, cool — almost subdued. He prefaced songs with “raps,” and they ran longer than typical standard of three minutes: One song, a cover of Glen Campbell’s “By the Time I Get to Phoenix,” ran 18 minutes.

“(Radio) jocks would play it at night,” Hayes recalled of his songs in a 1999 Associated Press interview. “They could go to the bathroom, they could get a sandwich, or whatever.”

Next came “Theme From Shaft,” a No. 1 hit from the blaxploitation film “Shaft” starring Richard Roundtree.

“That was like the shot heard round the world,” Hayes said in the 1999 interview.

At the Oscar ceremony in 1972, Hayes performed the song wearing an eye-popping amount of gold and received a standing ovation. TV Guide later chose it as No. 18 in its list of television’s 25 most memorable moments. He won an Academy Award for the song and was nominated for another one for the score. The song and score also won him two Grammys.

In 1972, he won another Grammy for his album “Black Moses” and earned a nickname he reluctantly embraced. He was also part of the historic “Wattstax” concert in riot-ravaged Watts neighborhood in Los Angeles.

Besides “Shaft,” Hayes composed film scores for “Tough Guys” and “Truck Turner.” He also did the song “Two Cool Guys” on the “Beavis and Butt-Head Do America” movie soundtrack in 1996.

Additionally, he was the voice of Nickelodeon’s “Nick at Nite” and had radio shows in New York City (1996 to 2002) and then in Memphis.

Though his last big hits on the charts ended in the 1980s, Hayes’ presence in contemporary music continued as his songs were sampled on numerous hits by rap and R&B performers, ranging from Ashanti to Public Enemy to Jay-Z.

“The rappers have gone in and created a lot of hit music based upon my influence,” he said. “And they’ll tell you if you ask.”

Stanback said: “A lot of artists owe Isaac his career because a lot of music was based on his foundation.”

He garnered another audience and cult following with his work on “South Park.” A school cook, Chef was in many ways the voice of reason in the otherwise outrageous animated social commentary, unwittingly imparting pearls of wisdom on the schoolboys who often came to him with their dilemmas; this, in spite of the fact that his foremost devotion was — true to Hayes’ music and persona — being a ladies’ man.

In the 1999 interview, Hayes described the character as “a person that speaks his mind; he’s sensitive enough to care for children; he’s wise enough to not be put into the ‘wack’ category like everybody else in town — and he l-o-o-o-o-ves the ladies.”

But Hayes angrily quit the show in 2006 after an episode mocked his Scientology religion. “There is a place in this world for satire, but there is a time when satire ends and intolerance and bigotry toward religious beliefs of others begins,” he said.

Co-creator creators Matt Stone responded that Hayes “has no problem — and he’s cashed plenty of checks — with our show making fun of Christians.” A subsequent episode of the show seemingly killed off the Chef character.

Hayes remained active in entertainment, even as he became a senior citizen. His Web site listed upcoming appearances and he was making plans for his Stax album. Stanback said it was to include Hayes’ work on vintage tracks that he had left unfinished over the years.

“We were actually getting ready to schedule a trip to Memphis to talk to Isaac,” he said.

Stanback called his death a tragedy.

“Isaac Hayes was a wonderful human begin and his spirit will live long in the form of his music,” he said.