The author and creator of the hit wizarding adventure stories has been the subject of abuse and even death threats from activists who disagree with her stance on protecting sex-based rights for women.
Margolyes, 80, told the Radio Times: "There isn't one answer to all these trans questions. We all know people who are slightly pansy or a bit butch or whatever you call it.
"But I think the vituperation JK Rowling has received is misplaced. I don't know her at all. I admire her as a human being. She’s a generous woman, she’s a brilliant writer.”
The actor and TV presenter played Hogwarts herbology teacher Professor Sprout in the film adaptations of the Harry Potter books.
Many of the stars of the film have spoken out to publicly distance themselves from Rowling, after she was accused of transphobia following a series of posts she published on Twitter in June 2020. They include Daniel Radcliffe, Emma Watson and Rupert Grint.
Margolyes said she would be happy to mediate between Rowling and the Harry Potter cast in the debate, saying: “I would if anybody asked me."
The This Morning guest presenter had previously said she did not want to comment.
Magolyes said in July 2020: "It’s hugely complicated. Look at poor JK Rowling. She’s dived into the pool and got very wet... I was asked to make a public statement and I didn’t want to. I just thought I’ve made enough public statements.”
Rowling was 'cancelled' after she responded to a story with a headline that read: “Opinion: Creating a more equal post-COVID-19 world for people who menstruate.”
She tweeted: “‘People who menstruate’. I’m sure there used to be a word for those people. Someone help me out. Wumben? Wimpund? Woomud?”
The writer went on to publish an essay online in which she claimed - as a domestic violence survivor - that she felt allowing trans people to use single-sex bathrooms and changing rooms could be "offering cover to predators".
Radcliffe apologised to Harry Potter fans for Rowling’s comments, and actress Katie Leung, who played Cho Chang in the movies, also commented.
Watson, who starred as Hermione Granger in the franchise, said: "Trans people are who they say they are and deserve to live their lives without being constantly questioned or told they aren't who they say they are.
"I want my trans followers to know that I and so many other people around the world see you, respect you and love you for who you are."
Rupert Grint, who played Ron Weasley, said in a statement: “Trans women are women. Trans men are men. We should all be entitled to live with love and without judgment. I firmly stand with the trans community and echo the sentiments expressed by many of my peers."
Robbie Coltrane, 72, who played groundskeeper Hagrid, also defended Rowling.
He said previously: “I don’t think what she said was offensive really. I don’t know why but there’s a whole Twitter generation of people who hang around waiting to be offended.
“They wouldn’t have won the war, would they? That’s me talking like a grumpy old man, but you just think, ‘Oh, get over yourself. Wise up, stand up straight and carry on.’”
Watch: Miriam Margolyes breaks wind on live TV