William Joseph Bell, an Emmy award-winning daytime TV soap writer, producer, and co-creator of “The Young and the Restless” and “The Bold and the Beautiful,” died Friday in Los Angeles. He was 78 and had been suffering from Alzheimer’s disease, his publicist announced.

Bell’s career as a TV soap writer spanned more than four decades and earned him nine Emmy awards – three for his writing on “The Young and the Restless” and the rest for producing or writing “Days of Our Lives.”

But Bell’s soaps didn’t just win awards, they won a following with daytime TV viewers, particularly fans hooked on the lives and loves of the residents in the fictional Genoa City portrayed on “The Young and the Restless.” The CBS show has long held the no. 1 spot against other daytime soaps and is the top daytime soap opera, according to the latest Nielsen ratings.

Bell, a Chicago native, got his start in 1956 as a writer on the soap “Guiding Light.” A year later, he left to write for another soap, “As the World Turns.”

While working on “As the World Turns,” Bell joined his mentor, Irna Phillips, and created a spin-off for the soap on prime-time called “Our Private World.”

In 1966, Bell became head writer on “Days of Our Lives,” helping take what was at the time a flagging series into one of the top audience draws four years later.

In 1973, Bell teamed up with his wife, Lee Phillip Bell, and created “The Young and the Restless.”

The hour-long show was among the first serials in the 1970s to exploit America’s burgeoning youth obsession.

“He gave me the most incredible gift that any actress could ever wish to receive – a complex, multifaceted character, Nikki Newman, that has endured over 25 years and still remains compelling and challenging today, both to me, and to our audiences,” veteran “Restless” actress Melody Thomas Scott said in a statement.

In the late 1990s, Bell surrendered the head writer’s role at “Restless” but took over as executive producer.

Bell and his wife teamed up in 1987 to create another daytime stalwart: “The Bold and the Beautiful,” which also offered viewers plenty of attractive characters wrestling with romantic challenges.

“Bill Bell understood that daytime drama was not just about lavish weddings and extravagant remotes, but about the smaller, day-to-day moments between family, friends, and community filled with love, conflict, and human foibles,” said Rhonda Friedman, supervising producer of “Bold.”

Through his career, Bell’s writing and production work is credited with contributing to 15,000 episodes of TV daytime drama.

His three children also followed him into the business.

One son, Bill, is president of Bell’s TV production company. Another, Bradley, is head writer and executive producer on “Bold.” Daughter Lauralee is an actress on “Restless.”

In addition to his children and wife of 50 years, Bell is survived by eight grandchildren.