(CNN) Tilda Swinton has undergone more on-screen transformations than perhaps any actor of her generation -- but the Oscar winner's latest stunt has still managed to catch Hollywood by surprise.
Swinton has laid to rest months of internet speculation by reluctantly revealing that she is in fact the 82-year-old male actor Lutz Ebersdorf -- who was previously credited as playing Dr. Josef Klemperer in the upcoming movie "Suspiria."
Four hours of makeup was required every day to turn Swinton into an octogenarian man, the actress told The New York Times.
Her commitment to the role went above and beyond -- with Swinton even insisting on having fake genitalia made and attached, according to the movie's makeup artist, Mark Coulier.
Swinton also plays Madame Blanc in the remake of the 1977 Italian horror flick, released later in October, but her revelation puts an end to a long mystery surrounding Klemperer's role.
That character was originally credited to the "first-time actor" Ebersdorf. But online sleuths found that too far-fetched to believe, and speculation that Swinton was playing both roles began to circulate online after photos from the set were leaked.
The rumors were repeatedly denied by those involved in the movie. Director Luca Guadagnino told Yahoo in February: "That's a complete fake news. They made a picture of my actor Lutz Ebersdorf and they claimed it was Tilda in makeup. I don't know why and I don't know who."
Ebersdorf even had a profile on IMDb created for him to keep the mystique alive, and several news outlets reported he, and not Swinton, was playing Klemperer.
Asked why she kept the pretense up for so long, Swinton told The New York Times: "I would have to say, for the sheer sake of fun above all.
"As my grandmother would have it -- a motto to live and die by -- 'Dull Not To,'" she added.
She also said that her hope had been that the fake actor Ebersdorf would "die" while the movie was being edited, with an "In Memoriam" being added to the closing credits.
While this trick was one of the more elaborate of Swinton's distinguished career, it's not the first time she has made herself virtually unrecognizable for a role.
Her appearances in the "The Grand Budapest Hotel," "Snowpiercer" and the romantic comedy "Trainwreck" required similarly impressive makeup work.
Swinton also played a young David Bowie, appearing alongside the late musician himself, in the music video for his 2013 single "The Stars (Are Out Tonight)."
She won a best supporting actress Oscar in 2008 for her role as an attorney in the legal thriller "Michael Clayton."