3. James Gordon Jr.
Barbara isn’t Commissioner Gordon’s only child. But while Babs grew up to be a hero, James Jr. went down a different path. Afflicted from childhood with severe antisocial personality disorder, James Jr. swiftly became as monstrous as his father and sister are noble.
Writer Scott Snyder brought him back into Detective Comics as a foil for his father, who had to discern whether or not his son was truly trying to better himself, or simply faking it to get close to his family again. But he soon moved from there to Batgirl, where he discovered his sister’s alter ego and began plotting against her. James Jr. even recently did a stint in the Suicide Squad.
James Jr. would be an ideal nemesis for Batgirl. It would give the film and the character an opponent with specific ties to Barbara, rather than borrowing someone from Batman’s rogues gallery that Matt Reeves hasn’t called dibs on. Plus, it would give the villain arc some emotional heft: sibling rivalry painted in the bright colors of superhero conflict.