One thing that might surprise rather than shock the fans about Marilyn Monroe, is that she was nothing like the ditsy character she played on-screen. Monroe didn’t have a brilliant formal education but she wasn't a dunce by any means.
I heard Marilyn Monroe's voice during an excerpt from an interview she gave and I was surprised at how different she sounded.
**UPDATE** - I am staggered by the continuing number of views, regarding my Marilyn Monroe answer. My humble thanks!!