Actress June Brown, who played the much-loved character Dot Cotton on EastEnders for more than three decades, has died at the age of 95.
Her family said they were "deeply saddened" to announce that their "beloved mother" had died "very peacefully" at her home on Sunday.
EastEnders actor Adam Woodyatt described her as an "incredible woman".
Dot Cotton was one of the BBC soap's longest-running characters and a favourite with viewers.
Brown first appeared in the series in 1985, the year EastEnders was created.
She stayed until 1993, returning to play the same character from 1997 until 2020.
An EastEnders spokesperson said: "There are not enough words to describe how much June was loved and adored by everyone at EastEnders, her loving warmth, wit and great humour will never be forgotten.
"June created one of the most iconic characters in Dot Cotton, not just in soap but in British television, and having appeared in 2884 episodes, June's remarkable performances created some of EastEnders finest moments."
After Brown's death was announced, many fans began sharing their favourite TV moment of hers - when the actress met Lady Gaga on the BBC's Graham Norton show.
One of EastEnders' best-known stars, Brown was in her late 50s when she joined Albert Square.
Actor Leslie Grantham, who played Dirty Den, suggested her for the role. Until then, Brown's career had incorporated stage, film and television, with appearances in Coronation Street and Doctor Who.
Some of her biggest storylines included Nasty Nick's murder plot, when her son, played by John Altman, planned to poison her so he could steal her big bingo winnings to use on drugs. He changed his mind at the last minute.
One of her most moving and controversial moments came when her close friend Ethel, who was terminally ill, asked Dot to help her take an overdose of morphine to end her life.
Dot wrestled with her Christian beliefs but ultimately decided to leave out morphine pills for Ethel to take.
Her relationship with husband Jim Branning, played by the late John Bardon, was much cherished by fans of the soap.
Brown remained a favourite with viewers for years, but during a podcast interview in February 2020, she confirmed that she had left the series "for good".
In the last episode she featured in, Dot Cotton - or Dot Branning - left a voicemail message for another character, Sonia Fowler, saying she had moved to Ireland.
Following the news of Brown's death, Woodyatt - who played Ian Beale in the soap for 35 years - said in a statement: "I'm lost for words, something June never was.
"So many memories, so much fun. Just purely and simply an incredible woman who had the most incredible life and career, I was fortunate to have shared a small part of it. They never made you a Dame (we did try), but to me you will always be Dame Brown."
Gillian Taylforth, who plays Kathy Beale in the BBC soap, said: "I'm truly heartbroken by this news. June Brown OBE, MBE, was an amazing woman and a truly wonderful actress. I shared many scenes with her over the years and she was always someone I looked up to and learnt from. There will never be another June Brown and I'm sending all my love to her family."
Culture Secretary Nadine Dorries said Brown was a "true national treasure".
"There was nobody quite like June Brown. She captured the zeitgeist of British culture like no other in her many years on our screens," she said.
"Today we've lost a true national treasure but my goodness what a life she has led. Rest in peace."
EastEnders executive producer Chris Clenshaw said Brown was an "iconic" character both on and off screen.
The BBC's director-general Tim Davie said: "June Brown was a brilliantly talented actor who was loved by millions. Her performances as the incomparable Dot Cotton delivered some of the most memorable moments in soap history."
"Our thoughts are with her family and many friends."
1/3“We are deeply saddened to announce that our beloved June Brown, OBE, MBE sadly passed away last night. There are not enough words to describe how much June was loved and adored by everyone at EastEnders, her loving warmth, wit and great humour will never be forgotten... pic.twitter.com/7OYtHJiIUb— BBC EastEnders (@bbceastenders) April 4, 2022
After she left the soap, Brown starred in a Christmas drama podcast in December 2020 as part of a series about family separation during the pandemic.
She played the mother of a son with Down's syndrome in the play, which explored the strains of the mother-son relationship during enforced isolation.
Other tributes were paid by former EastEnders star and activist Michael Cashman, who played the UK's first gay character in a soap opera, Colin Russell.
He wrote: "She took this country on an amazing journey and changed it for the better."
Cashman has previously spoken about how Brown helped him get time off rehearsals so he could go to an anti-Section 28 protest in London in 1988.
Actor and writer Stephen Fry also said Brown will be remembered "as a tireless and fearless LGBT ally".
He tweeted: "June Brown, amongst all her other wonderful human qualities and achievements, will be remembered as a tireless and fearless LGBT ally - especially during the darkest days of HIV/AIDS and Section 28... it was a privilege to know her."
Comedian Mo Gilligan also posted on Twitter: "If you grew up on an estate there was always a Dot Cotton. Absolute iconic character in EastEnders."