How much do ordinary people know about Batman? In a world full of super powers, cyborgs, time travellers, magic and aliens, do they know they know that Batman is a mere mortal in a costume? Would they think he has super powers? Maybe they think that he actually IS a bat, like Kirk Langstrom.
What about his allies and enemies? Do the Riddler, Penguin, and Two-Face know he’s just human? How about Jim Gordon and Harvey Bullock? How about other superheroes? Close friends know, but what about Guy Gardner, for instance?
So, ordinary people in the real world* aren’t as real as those in Gotham?
But my answer (after a surprising amount of thought) is that both groups of people DO know he’s mortal. I asked my mates at the pub, and they all knew.
One said “His super-power is that he’s a raving psycho who dresses up crazy.” I pointed out that that’s scarier than heat vision or spider webs… Batman seems like he might snap and break all your limbs in two manic minutes.
*I’m sure you’d think of it as “Earth Prime” (DC), or “Earth-616” (Marvel)
Depends on the continuity and sometimes the time period within it, but as things currently stand in the main universe…most do. He generally interacts with the people he saves, is a public member of the Justice League, and has a lot of flashy gear, rather than doing anything that would look like he’s a metahuman, or even equipped with tech beyond what Wayne Enterprises (or LexCorp, or Queen Industries, or Stagg, etc) could build.
I’d say Gordon knows that Batman is a human being. He may even have an idea he’s Bruce Wayne, but at least Gordon knows Batman’s human. He’s seen him injured enough times. His enemies know he’s human, too. They’ve tried to kill him often enough. The Riddler probably knows who he is. Selina Kyle definitely knows he’s Bruce Wayne. She was engaged to him.
Other superheroes know he’s human. Most of the members of the Justice League know his secret identity.
As someone else wrote it depends on where and when in the timeline you are. I varies from where was thought of as an urban legend and some people don’t believe he exists at all to where he is a known hero who people believe is bank rolled by the Waynes.
He started out as an urban legend but became better known later. I remember one JLA issue where he was complaining that he’d had too much exposure to remain the mysterious figure he started out as.
One thing people think they know about Batman, and that he does nothing to dispel, is the belief that he will summarily kill criminals. Comes in handy when dangling informers off the edge of a skyscraper.
If I got to write a Batman story arc (how 'bout it, DC?), I’d include a subplot with James Gordon as the Relatively Less Crazy Crimefighter of Gotham.
Now, he did plenty of sleuthin’ as a young detective, and he would want to know who he’s dealing with. Before he trusted Batman, he would’ve found out who he really was.
Now, would he be relieved that it’s someone he knows, would he see Bruce as one of the good guys, or at least invested in keeping Gotham safe? Or (since he’d also researched Thomas and Martha, and young Bruce’s trauma) would he be uneasy about a masked vigilante with “all those toys” and a hairpin trigger?
ETA: But he’d never let on that he knew. Unless some life-and-death scenario came up… (thanks to some hack writer [raising my hand])
No, Gordon wouldn’t let on if he knew Batman was Bruce Wayne. As he once put it to Batman, if word got out among the criminal element that he knew Batman’s identity, he would be tortured to get the secret out of him and Batman’s effectiveness as a crimefighter would come to an end.
There was a great one-off story from the early 70s era in which Bruce Wayne takes a group of young, under-priviledged kids from Gotham City on an overnight camping trip. Around the campfire, the kids begin talking about Batman and each kid takes a turn telling what they think they know about the Batman. The stories, as campfire tales told by kids often do, become more and more outlandish in the telling as the kids begin imagining the Batman as some kind of mutant bat-creature (akin to Man-Bat) or someone more like Superman.
I don’t know what issue of Batman (or Detective Comics) it was originally published in, I read it in one of those oversized collection editions. But it was a nice idea to have ordinary people (the kids) give their perspective on what the Batman is or looks like.
Batman 250, July 1973, story The Batman Nobody Knows. The B:TAS episode Legends of the Dark Knight, and the Batman: Gotham Knight segment Have I Got a Story For You were also both based on that story.
He is talking Gotham City obviously.