Sir Ian (left) said he "couldn't be happier" to be working with Stewart
Sir Ian McKellen is to tread the boards next year with X-Men co-star Patrick Stewart in a new staging of Samuel Beckett's 1955 play Waiting for Godot.
The production, which will be directed by Sean Mathias, will tour the UK before opening in London in April at the Theatre Royal Haymarket.
Stewart will play the tramp Vladimir, while Sir Ian will play Estragon.
The actors previously played comic book adversaries Professor X and Magneto in the three films in the X-Men series.
The pair first worked together at the Royal Shakespeare Company in 1977 in Tom Stoppard's Every Good Boy Deserves Favour.
Stewart is currently playing Claudius and the Ghost in the RSC's Stratford-upon-Avon production of Hamlet, which transfers to the West End later this year.
McKellen - also known for his role as Gandalf in the Lord of the Rings films - made his last stage appearance in the RSC's acclaimed staging of King Lear.
The actor said he "couldn't be happier". "There are no more juicy parts amongst modern classics than Didi and Gogo," he wrote on his official website.
The play will tour the UK before opening in London
Meanwhile, theatre producers have hit back at newspaper claims that West End ticket sales have been adversely affected by the so-called "credit crunch".
"I'm not pretending that there aren't shows out there having a difficult time, but I think it's related to all sorts of things," Michael McCabe, executive producer of the musical Wicked, told the Stage newspaper.
"Shows closing and coming in is a natural evolution," agreed David Schrader of the Disney Theatrical Group.
"No industry is going to be immune, but so far we're having a healthy autumn," said producer Nica Burns, whose current shows include Rain Man with Hollywood star Josh Hartnett.