Suicide Squad director, David Ayer, recently posted a pic on Twitter of the Gotham City villain, Black Mask. The pic can be seen below:
This may just be speculation but Ayer did the same thing last year when he posted the public's first look at Jared Leto's Joker on his Twitter account. Black Mask, who we know as Roman Sionis, was born to wealthy parents similar to Thomas and Martha Wayne. They however, cared little for their son, and more concerned with their social status and vices. Sionis eventually killed his parents and took over the cosmetics company. After one of his products deformed several women, Bruce Wayne offered to bail out the company but Sionis refused. After making a mask out of his father's casket, he transformed himself into the crime lord, Black Mask. He lead the False Face Society, where his minions also wore masks and wreaked havoc on Gotham through crime, drugs and corruption.
Until we get an official announcement, Black Mask may very well be the main villain, or it could also be a misdirection. The image that Ayer posted is from the comic "Batman: Under the Red Hood", so it could also mean we could see our first live-action interpretation of the Red Hood character, which has made waves in recent years. In recent comics as well, Black Mask and Catwoman, who is a confirmed Gotham Siren, are at odds as both are warring crime lords, vying for territory in Gotham.
David Ayer will produce and direct with Margot Robbie serving as an Executive Producer.