Main heroes like Superman, Batman, and Wonder Woman are going to be at the forefront of Zack Snyder's Batman v Superman: Dawn of Justice, but given the magnitude of the project, every single character in the film is going to be dissected by fans. It's not every movie where a bit player like Bailey Chase can become subject of much speculation.
A while back, the casting of Jena Malone sparked many theories about who she might be playing, with the prominent belief being she was set to portray the Carrie Kelley version of Batman's sidekick Robin. However, according to the latest rumor, Malone is actually playing a different character with ties to the Caped Crusader: Barbara Gordon.
The news comes courtesy of Latino-Review, who are citing multiple sources that claim Malone is indeed playing Barbara. Still, since the rumor mill for projects like Batman V Superman is always churning (see the latest reports on Chris Pine's role in the DC Extended Universe), it's best to take this development with a grain of salt until official confirmation comes from Warner Bros.
For those not in the know, Barbara Gordon is an important character in the Batman mythos. She is the daughter of Gotham police commissioner Jim Gordon, and in the DC comics universe she assumes the persona of Batgirl, another one of the Dark Knight's accomplices. She went by that alter-ego until the Killing Joke story, where the Joker crippled Barbara and left her confined to a wheelchair. Following that incident, she went by the name Oracle and aided her superhero allies by operating a worldwide communications network.
As L-R's report was brief, it's difficult to say if this is the plan for Malone's iteration of Barbara (considering this is true). Given all Batman V Superman has to unpack, Snyder throwing someone like Batgirl into the mix now would be him biting off more than he could chew. That said, it wouldn't be out of the question to introduce Barbara now in a small part and expand her role in future films (which is standard practice for a shared movie universe such as this).
The involvement of a member of the Gordon family would be an interesting development to feature in Dawn of Justice. Months ago, another unconfirmed rumor stated that Commissioner Gordon will be dead by the time the events of Batman V Superman take place. Regardless, the status of the Gordons will be yet another aspect of the film that is open for debate, as fans will be trying to figure out how all the pieces fit into the new DCEU. As the comics have shown, there are many different ways the filmmakers can take a character like Barbara.
There's still very much the possibility that Malone is playing someone else entirely (like Robin); we may not know for certain until the film comes out, since Malone is unlikely to have a larger role in the film's marketing campaign. In the meantime, as fans ponder the new official details about Batman V Superman, the rumor mill is still having its day in the sun.
Batman V Superman: Dawn of Justice opens on March 25th, 2016; Suicide Squad on August 5th, 2016; Wonder Woman on June 23rd, 2017; Justice League on November 17th, 2017; The Flash on March 23rd, 2018; Aquaman on July 27th, 2018; Shazam on April 5th, 2019; Justice League 2 on June 14th, 2019; Cyborg on April 3rd, 2020; Green Lantern Corps on June 19th, 2020.