'The Flash': 7 Mystery Girl Theories

Earth-11 Barry Allen

One of the theories we think is a longshot, but the Mystery Girl could be a gender-swapped version of Barry Allen from Earth-11.

In comics, Earth-11 is a world where the largest difference is that genders have been swapped. On Earth-11, Superman is Superwoman, Wonder Woman is Wonder Man, and the earth is more matriarchal. On Earth-11 The Flash would also be female -- a "Carrie" Allen, let's say. Considering that the Mystery Girl appeared during an invasion from Earth-X (the designation for Earth-10), the idea that an Earth-11 hero might hop over to Earth-1 isn't that huge of a stretch, even if her motivation for doing so remains a mystery. However, if Earth-11 were in danger, or even if Earth-11's heroes were villains, it could set up a situation where Barry and Team Flash have to deal with a threat from the multiverse in Season Five.

Nora Allen

During this season's premiere, Barry returned from the Speed Force but he wasn't quite himself. For a little while the speedster was seen writing strange symbols on every surface he could as well as rambling nonsensically. One of the things he said? "Nora shouldn't be here."

At the time fans thought that it was a reference to Barry's late mother, but one theory suggests that it's a reference to his and Iris' daughter. Considering just how much of a significance Nora had on Barry's life -- he even messed up the timeline to go into the past to save her -- it certainly wouldn't be out of the cards for him give his child the same name. It would also make for an interesting twist to the theory that the Mystery Girl is related to Barry and Iris, as most fans have speculated since her first appearance.

Dawn Allen

While the Nora Allen theory is a good one, many fans think that the Mystery Girl may end up being a much more familiar daughter of Barry and Iris: Dawn Allen.

In comics, Barry and Iris have twins, Dawn and Don Allen better known as the Tornado Twins and it's a possibility that the show's take on the "Trial of the Flash" storyline may have set up. In the comics, Dawn and her brother are conceived in the 30th century, after Barry runs to that point in time post-trial. While it's unknown exactly how that could unfold on The Flash - and if the show would even want to venture that far in the future - the idea of Barry and Iris rekindling their relationship post-trial certainly doesn't seem out of the cards.

Jenni Ognats

Another possibility is that the Mystery Girl isn't Barry and Iris' daughter, but it's also possible that she's their granddaughter, Jenni Ognats.

In comics, Jenni is Dawn Allen's daughter and happens to be a member of the Legion of Super-Heroes, the heroine XS. There would even be some comic book canon that the show could tap into if the Mystery Girl is Jenni. During the Legion's first trip to the 20th century, XS was separated from the rest of the team. She ended up interacting with people who were, functionally, her ancestors. Jenni specifically became friends with her cousin, Bart Allen.

With the Legion part of the Arrowverse via Supergirl, this is a real possiblity.

Joe and Cecile's baby

What if the Mystery Girl is family, just not Barry and Iris' child? That's the question behind the theory that the Mystery Girl is really Cecile and Joe's daughter.

Fans cite the fact that the Mystery Girl's appearance would work for Joe and Cecile to be her parents and her personality could be explained by a close relationship with her brother/brother-in-law Barry. It would also explain why she seemed interested in interacting with each of the members of Team Flash as they are likely people she grew up knowing or hearing about. It would also explain why she was so surprised and happy giving Cecile the baby bag. If she happens to be the soon-to-be-newest member of the family, it would have been a moving and special moment for her.

Cisco and Gypsy's daughter

This theory is another longshot considering that Gypsy (Jessica Camacho) and Cisco ended their relationship recently, but some fans still have hope that the pair will reconcile in the future and that could make the Mystery Girl their daughter.

Many of the attributes people have used to prove the Mystery Girl to be Dawn or Jenni also works for a child of Cisco and Gypsy. The skin pigmentation would be similar, as would the awkward personality and fluency with scientific jargon. The nerdy T-shirts are a new addition to the Mystery Girl puzzle, but it's one that leans more towards Cisco, who is well-known for his collection of awesome T-shirts throughout the series. Making the girl a future child of Cisco and Gypsy would also explain a bit more why she was seen writing Barry's mysterious symbols in her journal. As Gypsy is from another Earth and spends her time chasing down dimensional criminals, it wouldn't be too much of a stretch to think that a child between Cisco and Gypsy would spend a lot of time on other Earths too. That might be where she learned the unusual writing.

Reverse Flash

This last theory might be the most grim, but it's one that we think is certainly possible.

During the final hour of "Crisis on Earth-X" Reverse Flash/Eobard Thawne (Tom Cavanagh) tells Barry "I wonder what face I'll be wearing next time we meet, Flash." What if that face is one of the Mystery Girl? It's a curious theory and one that, while incredibly different from previous ones, is somewhat plausible. However, it's equally as possible that while the Mystery Girl isn't Reverse Flash herself she may well still be a Thawne. In comics, Barry and Iris have twins, Dawn and Don Allen. While Dawn goes on to marry Jeven Ognats and give birth to Jenni, who later becomes the Legionnaire XS, Don marries Meloni Thawne. They have a son, Bart Allen. It's not completely crazy to think that the Mystery Girl could be a take on Bart Allen, bringing Reverse Flash back into the equation in the process.

The Flash's season 4 finale, "We Are The Flash", airs Tuesday, May 20 at 8/7c on The CW.

Who do you think the Mystery Girl will end up being? Let us know in the comments below!