The pair were students together at Cambridge University, which is where she met the comic and actor.
In her new autobiography, This Much is True, she said the way Cleese behaved towards her was “diminishing, pointed and vicious” and also criticised Cleese’s late Monty Python co-star Graham Chapman for treating her as poorly.
The Harry Potter actor also alleged that Bill Oddie, Tim Brooke-Taylor, Tony Hendra and Humphrey Barclay all acted extremely negatively towards her.
She said that the behaviour of the group of comics, who were all part of the Cambridge Footlights theatre club, along with Margolyes, made her “weep in her bedroom” and had her feeling “invisible”.
“John Cleese, Bill Oddie and Graham Chapman were total s***s and they have never apologised. The only one who did was the late Tim Brooke-Taylor.”
Margolyes also says she was “the only girl in the show, I was a pert little madam and thought I was as good as they were and they didn’t.”
Elsewhere in the extract from the book, the actor claims that the group also looked down on future TV presenter David Frost, because he was a “middle-class lad from Gillingham” and writer Clive James – because he was from Australia.
Margolyes concluded by summarising her opinion on the comedians: “I admire the creation of Monty Python and The Goodies and I think they were men of genius, but they were not gentlemen.”