Ruth Brown, the gutsy rhythm and blues singer whose career extended to acting and crusading for musicians’ rights, died on Friday in Las Vegas. She was 78 and lived in Las Vegas.

The cause was complications following a heart attack and a stroke she suffered after surgery, and Ms. Brown had been on life support since Oct. 29, said her friend, lawyer and executor, Howell Begle.

“She was one of the original divas,” said the singer Bonnie Raitt, who worked with Ms. Brown and Mr. Begle to improve royalties for rhythm and blues performers. “I can’t really say that I’ve heard anyone that sounds like Ruth, before or after. She was a combination of sass and innocence, and she was extremely funky. She could really put it right on the beat, and the tone of her voice was just mighty. And she had a great heart.”

“What I loved about her,” Ms. Raitt added, “was her combination of vulnerability and resilience and fighting spirit. It was not arrogance, but she was just really not going to lay down and roll over for anyone.”

Ms. Brown sustained a career for six decades: first as a bright, bluesy singer who was called “the girl with a tear in her voice” and then, after some lean years, as the embodiment of an earthy, indomitable black woman. She had a life of hard work, hard luck, determination, audacity and style. Sometimes it was said that R&B stood as much for Ruth Brown as it did for rhythm and blues.

As the 1950s began, Ms. Brown’s singles for the fledgling Atlantic Records — like “(Mama) He Treats Your Daughter Mean” and “5-10-15 Hours” — became both the label’s bankroll and templates for all of rock ’n’ roll. She could sound as if she were hurting, or joyfully lusty, or both at once. Her voice was forthright, feisty and ready for anything.

After Ms. Brown’s string of hits ended, she kept singing but also went on to a career in television, radio and movies ( including a memorable role as the disc jockey Motormouth Maybelle in John Waters’s “Hairspray”) and on Broadway, where she won a Tony Award for her part in “Black and Blue.” She worked clubs, concerts and festivals into the 21st century.

“Whatever I have to say, I get it said,” she said in an interview with The New York Times in 1995. “Like the old spirituals say, ‘I’ve gone too far to turn me ’round now.’ ”

Ms. Brown was born Ruth Weston on Jan. 12, 1928, in Portsmouth, Va., the oldest of seven children. She made her debut when she was 4, and her father, the choir director at the local Emmanuel African Methodist Episcopal Church, lifted her onto the church piano. In summers, she and her siblings picked cotton at her grandmother’s farm in North Carolina. “That made me the strong woman I am,” she said in 1995.

As a teenager, she would tell her family she was going to choir practice and perform instead at U.S.O. clubs at nearby naval stations. She ran away from home at 17, working with a trumpeter named Jimmy Brown and using his last name onstage. She married him, or thought she did; he was already married. But she was making a reputation as Ruth Brown, and the name stuck.

The big-band leader Lucky Millinder heard her in Detroit late in 1946, hired her for his band and fired her in Washington, D.C. . Stranded, she managed to find a club engagement at the Crystal Caverns. There, the disc jockey Willis Conover, who broadcast jazz internationally on Voice of America radio, heard Ms. Brown and recommended her to friends at Atlantic Records.

On the way to New York City, however, she was seriously injured in an automobile accident and hospitalized for most of a year; her legs, which were smashed, would be painful for the rest of her life. She stood on crutches in 1949 to record her first session for Atlantic, and the bluesy ballad “So Long” became a hit.

She wanted to keep singing ballads, but Atlantic pushed her to try upbeat songs, and she tore into them. During the sessions for “Teardrops From My Eyes,” her voice cracked upward to a squeal. Herb Abramson of Atlantic Records liked it, called it a “tear,” and after “Teardrops” reached No. 1 on the rhythm and blues chart, the sound became her trademark for a string of hits.

“If I was getting ready to go and record and I had a bad throat, they’d say, ‘Good!’,” she once recalled.

Ms. Brown was the best-selling black female performer of the early 1950s, even though, in that segregated era, many of her songs were picked up and redone by white singers, like Patti Page and Georgia Gibbs, in tamer versions that became pop hits. The pop singer Frankie Laine gave her a lasting nickname: Miss Rhythm.

Working the rhythm and blues circuit in the 1950s, when dozens of her singles reached the R&B Top 10, Ms. Brown drove a Cadillac and had romances with stars like the saxophonist Willis (Gator Tail) Jackson and the singer Clyde McPhatter of the Drifters. (Her first son, Ronald, was given the last name Jackson; decades later, she told him he was actually Mr. McPhatter’s son, and he now sings with a latter-day lineup of the Drifters.)

In 1955 Ms. Brown married Earl Swanson, a saxophonist, and had a second son, Earl; the marriage ended in divorce. Her two sons survive her: Mr. Jackson, who has three children, of Los Angeles, and Mr. Swanson of Las Vegas. She is also survived by four siblings: Delia Weston of Las Vegas, Leonard Weston of Long Island and Alvin and Benjamin Weston of Portsmouth.

Her streak of hits ended soon after the 1960s began. She lived on Long Island, raised her sons, worked as a teacher’s aide and a maid and was married for three years to a police officer, Bill Blunt. On weekends she sang club dates in the New York area, and she recorded an album in 1968 with the Thad Jones-Mel Lewis Big Band. Although her hits had supported Atlantic Records — sometimes called the House That Ruth Built — she was unable at one point to afford a home telephone.

The comedian Redd Foxx, whom she had once helped out of a financial jam, invited her to Los Angeles in 1975 to play the gospel singer Mahalia Jackson in “Selma,” a musical about civil rights he was producing.

She went on to sing in Las Vegas and continued a comeback that never ended. The television producer Norman Lear gave her a role in the sitcom “Hello, Larry.” She returned to New York City in 1982, appearing in Off Broadway productions including “Stagger Lee,” and in 1985 she went to Paris to perform in the revue “Black and Blue,” rejoining it later for its Broadway run.

Ms. Brown began to speak out, onstage and in interviews, about the exploitative contracts musicians of her generation had signed. Many hit-making musicians had not recouped debts to their labels, according to record company accounting, and so were not receiving royalties at all. Shortly before Atlantic held a 40th-birthday concert at Madison Square Garden in 1988, the label agreed to waive unrecouped debts for Ms. Brown and 35 other musicians of her era and to pay 20 years of retroactive royalties.

Atlantic also contributed nearly $2 million to start the Rhythm and Blues Foundation, which pushed other labels toward royalty reform and distributed millions of dollars directly to musicians in need, although it has struggled to sustain itself in recent years.

“Black and Blue” revitalized Ms. Brown’s recording career, on labels including Fantasy and Bullseye Blues. Her 1989 album “Blues on Broadway” won a Grammy Award for best jazz vocal performance, female. She was a radio host on the public radio shows “Harlem Hit Parade” and “BluesStage.” In 1995 she released her autobiography, “Miss Rhythm” (Dutton), written with Andrew Yule; it won the Gleason Award for music journalism. She was inducted into the Rock and Roll Hall of Fame in 1993.

She toured steadily, working concert halls, festivals and cabarets. This year she recorded songs for the coming movie by John Sayles, “Honeydripper,” and was about to fly to Alabama to act in it when she became ill.

Ms. Brown never learned to read music. “In school we had music classes, but I ducked them,” she said in 1995. “They were just a little too slow. I didn’t want to learn to read no note. I knew I could sing it. I woke up one morning and I could sing.”