Marco Mancassola, an Italian author, has outed Batman in his book, Erotic Lives of The Superheroes, set to release in U.K. this week.
The author told The Independent that Batman also "indulges in weird forms of fetishism and extreme sex."
In the book, first published in Italy in 2008, Batman and Robin are a bickering couple with a waning sex life.
Besides being openly gay, Batman is also portrayed as having "a dark side."
Mancassola told The Independent:
"Narcissism is his inner abyss. He let his only real love story miserably fail because he is in love with the mystery of youth – that inaccessible, fleeting kind of spirit that he sees in the eyes of his young male and female pick-ups."