Actress and singer Bernie Nolan has died at the age of 52, following a long battle with breast cancer.
The former lead singer of The Nolans was first diagnosed in 2010, and had chemotherapy and a mastectomy, receiving an all-clear in 2012.
However, months later the disease returned and spread to her brain, bones, lungs and liver.
In recent years she was best known for her acting roles in The Bill and Channel 4 soap Brookside.
"Bernie passed away peacefully this morning with all of her family around her," said a spokesperson for the family.
"The entire family are devastated to have lost beloved Bernie, a wonderful wife, adoring mother and loving sister, she is irreplaceable."
Born on 17 October 1960, she grew up in Ireland, performing as a family troupe with her five sisters and two brothers. Her father Tommy would go on to be the Nolans' manager - but after his death, eldest sister Anne revealed he had sexually abused her from the age of 11.
Nolan turned to acting following 20 years fronting the Irish all-girl group and a string of hits including 1979's I'm in the Mood for Dancing and Don't Make Waves.
She left the group in 1994, and took to the stage, performing in productions including Blood Brothers in London's West End, Flashdance and a UK tour of Chicago the Musical.
She moved into television playing hairdresser Diane Murray in Brookside from 2000-02 and joining ITV's police drama The Bill in 2003, as Sergeant Sheelagh Murphy.
"So sad to hear Bernie Nolan has passed away," tweeted Nolan's Brookside co-star Jennifer Ellison, after hearing the news of her death. "Such an amazing lady, had the honour of working with her twice will cherish the memories."
Bill co-star Gary Lucy tweeted: "RIP Bernie Nolan - our thoughts are with her family."
Nolan also took part in ITV's talent show Popstar to Operastar in 2010, reaching the final but losing to Pop Idol's Darius.
In 2008, Bernie, Maureen, Linda and Coleen agreed to a multi-million pound reunion tour of The Nolans with Universal Records, prompting a feud between the two remaining sisters, Denise and Anne.
Anne, who was in the original line-up but left the group for two years at the height of their mainstream success, was not included by the tour's producers and it caused a bitter rift. Denise had left the group before any of the group's chart hits.
"Despite all the drama around it, doing the show was one of the best things I've ever done. It gave us all something to remember for ever," Bernie said in her autobiography Now & Forever, which was published in May this year.
In the book, she claimed she had made her peace with all five of her sisters over the last few years - and urged her sisters to do the same. Two of her five sisters, Anne and Linda, were previously diagnosed with breast cancer but overcame the disease.
Presenter Lorraine Kelly paid tribute on Thursday, tweeting: "Bernie Nolan was a very special woman. Brave, funny and hugely talented. She will be sorely missed. Thoughts with her family and friends."
Sherrie Hewson, who works with Bernie's sister Coleen on Loose Women, tweeted: "RIP the wonderfully talented Bernie Nolan. A beautiful person that brightened up this sometimes dark world of ours! Sing forever Bernie."
"Very sad to hear of the passing of Bernie Nolan," added commentator Gary Lineker on Twitter. "A fabulous and fabulously talented lady. Thoughts are with the family."
Bernie married Steve Doneathy in 1996 and leaves one daughter, Erin.
Speaking to BBC Breakfast in May this year, Mr Doneathy said she had stopped chemotherapy and entered palliative care.
"But she's still being as positive as you can be under those circumstances. You get up every day, face the day, and make that day the best it can be."