DAME Judi Dench, DAME Diana Rigg and Vanessa Redgrave are among the actors calling for London's Victoria And Albert Theatre Museum to remain open.
The museum, which houses a collection of stage costumes including SIR Laurence Olivier's outfit from Richard III, is facing closure after failing to raise $20.4 million (GBP12 million) for redevelopment.
In a letter to British newspaper The Times, the actors write: "We are horrified that this important and world-renowned museum could be closed and its collection broken up.
"We fear this means that most of the exhibits would no longer be available to the public."
Redgrave describes the possible closure of the nearly 20-year-old museum as "a catastrophe".