Veteran TV star June Whitfield is making a one-off appearance in Albert Square.
The actress, who starred in hits including Terry And June and Absolutely Fabulous, will appear in EastEnders opposite Jessie Wallace's character, Kat Moon, in a single episode this May.
She said: "I have watched EastEnders for years, and have been so impressed by the standard of acting. It was an absolute delight to work with Jessie Wallace and I am very excited to be part of the show."
The BBC One soap, which recently celebrated its 30th anniversary, will also feature a guest appearance from Jan Harvey.
The actress, who played Jan Howard in 1980s drama Howards' Way, said: "I loved working on such an iconic show. Everyone was so welcoming. EastEnders is really like one big family."
Show bosses are staying tight-lipped about who exactly the pair will play, but executive producer Dominic Treadwell-Collins said: "We are extremely privileged to have two British television legends joining us for guest roles as Albert Square heads into the spring.
"Both June and Jan are class acts, bringing warmth and humanity to two characters who will shed some light on the pasts of two of our most iconic women - Sharon Mitchell and Kat Moon - changing both their lives in very different ways."