Janine Malloy is set to meet her match when her gran joins EastEnders - played by stage veteran Margaret Tyzack.
She is heading to Albert Square in April to play maternal grandmother Lydia Simmonds.
The pair have been estranged since Janine (who was formerly Janine Butcher and who is played by Charlie Brooks) was a youngster.
Margaret, who has worked with the Royal Shakespeare Company, has won numerous plaudits for her stage work including a pair of Olivier Awards and a Tony.
The actress, who has starred alongside Dame Helen Mirren at the National Theatre and appeared opposite Dame Maggie Smith in Lettice and Lovage, has also made notable screen appearances.
They include two of Stanley Kubrick's films 2001: A Space Odyssey and A Clockwork Orange, and she is known for TV roles in classic series such as The Forsyte Saga and I, Claudius.
Margaret, 79, said: "I am delighted to be joining a great British tradition and a fine company of actors."
Snobbish Lydia ceased contact with her daughter June - Janine's mother - when she ran off with "common as muck" Frank Butcher.
The two generations find they have something in common when they are reunited - a bad reputation which causes people to avoid them.
Bryan Kirkwood, executive producer of the soap, said: "What a coup to have Margaret Tyzack starring in EastEnders. She is an actress of incredible class and talent. Lydia has endless possibilities as a character, and I can't wait to see Janine meet her match."