Found on Reddit, the art, credited to William Gray, shows McGregor as Roman Sionis, wearing the iconic skull mask, which appears to be made of Kevlar rather than steel, similar to how we've seen Batman's masks since Batman Begins. In the image, the villain's rendering is seen holding a gun that seems to have just been fired, a broken mask and of course, his signature suit, indicating he's been conducting business.
Huntress actress Mary Elizabeth Winstead just announced the film will start shooting in January, and castings have been picking up, with Ella Jay Basco being cast as Cassandra Cain. She's expected to be the uniting factor that brings the likes of Rosie Perez as Renee Montoya, Jurnee Smollett-Bell as Black Canary and Margot Robbie (returning as Harley Quinn) together to battle Black Mask.
First introduced in Batman #386 in 1985, Black Mask was created by Doug Moench and Tom Mandrake. In the comics, Black Mask is a businessman who squanders his inherited fortune and eventually opts to pursue a life of crime, all while blaming Bruce Wayne for his failings, although this could be altered for the DCEU.
Birds of Prey is currently targeting an R-rating, according to its director, with the expectation being that the film will be full of "dark humor."