EastEnders veteran Pam St Clement is to bow out of Albert Square, more than a quarter of a century after making her debut as no-nonsense Pat.
The actress, 69, one of the longest serving stars of the show, will leave Walford later this year.
St Clement said she had other things she wanted to do but said leaving the soap would be like a "bereavement".
During her colourful years in the show, Pat remarried several times, has gone to prison and enjoyed affairs with Walford characters such as infamous lothario Den Watts (Leslie Grantham).
St Clement joined the BBC1 show in 1986 - a year after it launched - and became noted for her dangly earrings and brassy bleached hairdo.
She was first seen after arriving in the Square to break the news to Pete Beale (Peter Dean) he was not the father of her son Simon Wicks (Nick Berry).
St Clement said: "I have enjoyed 25 and a half wonderful years in EastEnders creating the character of Pat but feel it's time to hang up her earrings. Leaving the EastEnders 'family' will be akin to a bereavement. But I'm looking forward to the other work and life opportunities that I will have the time to pursue."
Viewers have seen her marry Frank Butcher in 1989 and then her fourth husband, Roy Evans, in 1996.
Her most famous scenes over her long career have often been moments of high drama, often involving slaps.
In one memorable scene she and Peggy Butcher (Barbara Windsor) exchanged blows amid cries of "you bitch" and "you cow". In another climactic scene, Pat's affair with ex-husband Frank was exposed by Peggy in front of regulars at the Queen Vic, ending with slaps for the pair who had betrayed her.
Pat has also had a stint as the Vic's landlady, survived a heart attack, and been imprisoned for a hit and run.
The BBC would not say how she will leave the show at this stage. St Clement is second only to Adam Woodyatt - who plays Ian Beale - as the longest-serving member of the cast.
John Yorke, controller of BBC drama production, said: "It's always a sad day when one of our stars leaves EastEnders but when those stars are as important as Pam St Clement and the character as iconic as Pat Butcher the blow is doubly hard.
"Part of EastEnders' 'creation myth', she has been integral to the programme's success from the very beginning; her love of Frank, her 'take no prisoners' nature and her earrings have made her a part of British culture.
"For most actors that would be legacy enough. The fact that Pam is also a total professional, an endless champion of the programme and a joy to work with is an added bonus."
Executive producer of EastEnders Bryan Kirkwood, said: "Over the years we've seen her develop from a shrew into a matriarch, and Pat's colour, warmth and steel have given EastEnders some of its most memorable stories. Pam will be missed by everyone in Walford, and we wish her the very best of luck in everything that comes next."
He said her departure would be a "not to be missed" and "fitting" storyline.