Former Coronation Street actress Georgia May Foote and ex-EastEnders star Annette Badland are to appear in the 20th anniversary episode of Doctors.
Foote played Katy Armstrong on Corrie for five years before departing in 2015, and her character has since been killed off in an off-screen car accident.
Badland, meanwhile, played the villainous Aunt Babe in Walford for three years and was written out in 2017.
Doctors will celebrate 20 years on the air today with a special episode, 'A Day in the Life', which has been filmed in the style of a fly-on-the-wall documentary.
Executive producer Mike Hobson said: "Doctors has the unique ability to do something that no other continuing drama can do and we are incredibly lucky to work with such talented guest cast who work alongside our regular cast members.
"We have become known for our famous faces with literally hundreds having graced our screens over the past 20 years and we look forward to welcoming many more in the future."
The special episode airs today at 1.45pm on BBC One.