Barbara Windsor is to return to Walford for a one-off appearance - to deal with "family matters".
The 75-year-old actress, who played Peggy Mitchell for 16 years, will make her comeback to Albert Square three years after viewers last saw her.
The former Queen Vic landlady will be seen in the autumn when she learns that her eldest son Phil (Steve McFadden) needs her help.
Babs said: "It is no secret how much I have always loved EastEnders and Peggy Mitchell - and by the number of times I'm constantly stopped by the great British public and asked either 'when are you coming back' or please say 'Get out of my pub', it seems they have too.
"It may only be a short visit, but it's a family matter and as Peggy always said 'it's all about family'."
Her character headed off to Portugal following a devastating fire at the Vic and her heartbreaking realisation that quitting Walford was the best way for Phil to turn his life around.
Barbara's return will come at a dramatic time for the Mitchell clan, with Samantha Womack reprising her role as Ronnie Mitchell and Roxy planning her wedding to Alfie Moon. Phil will be seen in trouble once again.
Lorraine Newman, executive producer of EastEnders, said: "We're delighted to announce Barbara's return for a very special episode.
"Peggy's surprise visit is a wonderful treat for our fans, as well as the cast and crew here on EastEnders. It's great to welcome her home."