Severus Snape protecting the Harry Potter gang (Warner Bros)

Harry Potter theories are a way for fans to keep their favourite fictional world alive.

From the creator herself, JK Rowling, revealing that Dumbledore is gay to the fan theory Ronbledore, which suggests Ron and Dumbledore are the same person, these added extras to the actual storyline are a brilliant way to introduce new dimensions to the books and film.

One of the more recent theories is about Severus Snape: the former death eater who is besotted with Harry Potter’s mother, Lily.

Snape is portrayed as a pretty evil character for a good portion of the books but we soon come to realise that he has actually devoted his life to protecting Harry because of his love for his mother.

However a new theory has emerged, and it’s shockingly convincing.

Severus Snape is transgender.

This is a theory that has been built on for years now with avid fans studying the text closely, and it all started when author Racheline Maltese penned an essay insisting the Snape was a female heroine.

A lot of the reasoning behind Snape’s trans identity stems from his role in Harry’s life.

Some Tumblr users suggest that Snape is a “stand-in” for Lily as he protects Harry.

They also imply that Snape’s patrons (a doe) is the same as Lily’s not just because of the romantic interest he had for her, but because he wanted to be a woman like her.

Fans also allude to a flashback in The Deathly Hallows where a young Snape is wearing his mother’s clothes.

A final indicator is a scene in Prisoner of Azkaban where Neville Longbottom’s boggart is Snape.

Lupin casts a spell to transform the boggart so that Snape is wearing traditionally female clothing.

A user on Tumblr who is one of the biggest supporters of the theory, Ensnapingthesenses, explained that this “extremely personal mockery” of the transformed boggart was a “powerful example of the way in which Snape was shamed for being feminine.

The theory has been built on and celebrated largely by the trans community on Tumblr.

Ensnapingthesense, a 26-year-old trans man who lives in Spain, is one of the driving forces behind the community.

They said: “I can’t fathom Snape not being trans. The contextual clues all point to it.

“Snape is a character who inhabits a fluid, ambiguous position for most of the narrative—always between two worlds, and often quite literally lurking in the shadows of a room, outside looking in.

“Snape reads as someone in the closet, and tragically so.”

The theory is so popular that they have dedicated the first week of August to be celebrated as Trans Snape Week on Tumblr.

The event was created in 2015 by the user Ensnapingthesense.

The user has explained that the week is for the community to celebrate Snape and whatever his gender identity may be.

“Trans Snape Week is really just a place to get together and celebrate, explore, and share: It’s spawned all sorts of fanfiction, fanart, literary analysis… We see ourselves reflected in such a complex, interesting, and polarizing figure—which we don’t usually get to do, as transgender fans,” he told Broadly.