The actor, who can be seen in full costume in the video below, is not confirmed for a cameo in Zack Snyder's Justice League and DC Entertainment president Geoff Johns wouldn't confirm or deny rumors that he would be appearing. Neither Affleck or Johns have confirmed anything else about the actor's role, or if he'll be the only villain that Affleck's Dark Knight takes on.
Introduced to the world of DC Comics in the 1980s, Deathstroke was originally designed as the main antagonist that the teenage superhero group, Teen Titans, took on during their run. It was because of the character's success in the Judas Contract arc that Deathstroke received his own spinoff series and was integrated into other characters books.
There's currently no release date, or even an estimated release date, for Affleck's Batman movie. The actor will appear alongside Henry Cavill and Gal Gadot, as well as quite a few other actors, in Justice League. That hits theaters on Nov. 17, 2017.