As I mentioned in my post about the inclusiveness of the Star Wars setting, all kinds of characters could be translated into the Star Wars galaxy. I'm not sure if I'd use any of them in my campaign, but at the very least its a fun mental exercise. And so I'll explore one of my favorite characters: Batman.
First of all, he'd need an appropriate setting. I figure a heavily populated core-world. We'll call it "Gothas". I'd see it as a darker version of Coruscant, though not as entirely 'urbanized'. Picture sprawling city-scapes interspersed with gigantic spreads of rusting industrial parks and beyond those the majestic country estates of Gothas' wealthy (as well as a few gigantic planetary wildlife preserves). The architecture of the cities and estates could be from a bygone 'Gothic' era, complete with lots of ornamental sculptures and stonework.
Now that we have the setting, we'll need the story. Bruce Wayne was born to one of Gothas' wealthy families. His parents were professionals who built the family business into a corporate giant (at least within the system/sector). Though his parents were capitalists, they were also philanthropists and idealists, reinvesting their time and money into trying to make Gothas a better place. As Palpatine came to power, the idealism of Bruce's parents was put to the test, frequently running against the tightening noose of Imperial control and corruption.
The real story would start when Bruce was about eleven years old—some nineteen years BSW (before Star Wars), just after the end of the Clone Wars. His parents are killed right in front of him, while on the way home from a holo-show in the City—lost to a seemingly random act of criminal violence. Bruce was left to be raised by the family butler, Alfred, but upon coming of age, he dropped out of college and promptly disappeared.
For some ten years, Bruce wandered the outer-rim territories, dedicating himself to a vow he had made to his slain parents—he would fight crime and the corruption that fed it. He would do everything in his power to see that no other child would have to suffer as he had. To this end, he sought out specialists in various fields: combat, investigation, athletics—anything that would help mold him into the crime fighter he saw himself becoming. But he went further than this, delving into the underworld personally, learning its ins and outs by working with various criminal gangs. But never, not even once, would he compromise his principles. He would not kill. He would not harm the innocent. He would not forget his vow.
And so, when he turned thirty, when he felt he was finally prepared, he returned to Gothas. There, he set about the final stages of his plan. While publicly assuming the role of a trillionaire playboy, Bruce was secretly establishing a base of operations in the caves beneath his sprawling manor. Utilizing intellect and skill, along with the resources of his company, he was able to equip himself with the latest technological vehicles, defenses and gear.
Once all was in place, he began an undercover investigation into the underworld of Gothas, getting a feel for who the major players were. It was during this time that his suspicions were confirmed. The corrupt Imperial Governor of Gothas was in league with the various criminal gangs and there were even suggestions that the Governor had a hand in the death of Bruce's parents—evidently, their idealism was running counter to the Empire's best interests. So it was that the scope of Bruce's crusade widened. The Empire was a part of the corruption that had taken his parents. He would work to undermine it just as surely as he would take down all the other criminal bosses.
Bruce's initial forays into crime fighting didn't go smoothly. But he learned from his mistakes, refining both his equipment and his tactics—and ultimately adopting the alter-ego of 'Nightwing', named after the stealthy, nocturnal predators who inhabited the caves beneath his manor.
Considering how well-grounded Bruce Wayne is, it seems to me that all of his supporting cast can work just as easily.
Alfred: Translates without much change at all. He was the Wayne family Butler and Bruce's guardian on the death of his parents. He would continue to work as Bruce's assistant and confidant. Though I like the 'human touch' for Alfred, it might be interesting to cast him as a Droid instead of an organic. Picture C-3PO, only older and more dignified. Maybe.
Robin: Why not have a little punk- err.. a junior assistant to Nightwing. Though, in truth, Bruce stole Robins cooler name 'Nightwing' for himself in this reality. Oh well.
Batgirl: A much more preferable assistant for Nightwing, as she is a she, an she's hot. Still, not quite sure what to name her. Nightwing-Girl just doesn't have the right ring to it.
Commissioner Gordon: Yep. Works fine. He'd be the guy in charge of Gothas' planetary police force. A good a heart guy who tries to help Nightwing secretly while publically hunting for him. I figure he'd have to play the fence between the corrupt Imperial governor and Nightwing's idealistic crusade.
The Joker: Oh yes. Can't have Nightwing without this guy. I see him as the Heath Ledger type, an anarchist criminal—though one who occasionally takes work for the Empire (I can see a kook like him being recruited by Imperial Intel. Hell, he's a one-man Planetary Destabilization team).
Catwoman: Rowr. She could be her typical burglary self, but for a twist, she could be a feline-type species (Cathar or some such—though hopefully without the annoying Juhani accent).
Poison Ivy: Again, Rowr. She could be some plant-based humanoid species. Would work well with her pheromones and stuff. She could be the same pro-plant nut that she was in the comics/cartoons.
Two-Face: An idealistic Imperial political crusader who does his job just a bit too well. Before he completely uncovers corruption in his Imperial masters, they try to have him killed, botch it and wind up disfiguring him. From there, he goes insane and starts his own disillusioned crusade against everything he once supported.
Killer Croc: Yeah, sounds like a Barabel, or a Trandoshan—or some other big, muscly lizard-man capable of throwing big rocks.
The Penguin: Always thought he had the goofiest name. Still do. But the way he was presented in the Batman Cartoons I can live with: A well-dressed crime-boss and club-owner. For an interesting twist, what if he's some kind of alien species...maybe even a Hutt? Hmmm, possible.
Ra's al Ghul: Yeah, he'd work great in a Star Wars setting. You could replace his 'Lazarus Pit' stuff with some kind of dark-side alchemy that keeps him alive and going. He could even have an association with the Sith, being a minor Force User in his own right. Likewise, his daughter, Talia (once again, Rowr) could be a good femme-fatale foil for Nightwing.
The Riddler: Way too goofy.
USES IN CAMPAIGN
Though all of this was very fun, it would be a bit difficult to insert Nightwing into a Star Wars campaign without overshadowing the player characters. Still, it could work if you utilize him as a feature-character, perhaps by having the players visit Gothas and get involved in one of Nightwing's cases—teaming up to defeat a particular Imperial or Criminal villain. As I have established him here, Nightwing is pretty much the core of a Rebel 'Cell' on Gothas, and would likely work with the Alliance (as a free agent of course).