Eddie doesn’t know any more. He received a head injury at some point…that particular bit of knowledge was the only permanent casualty. [Edit - he was in a coma. See Detective Comics 822, October 2006, written by Paul Dini.]
That’s a matter of debate. The only thing we know for sure is that Bane knows though.
He did once. In 1960. For twenty minutes.
Correct me if i’m wrong, but didn’t Ra’s Al Ghul’s very first interaction with Batman occur when he kidnapped Dick Grayson in order to draw Batman’s interest?
The Robins, being sidekicks, are obviously combatants, and thus are fair game. I suspect Alfred is too. But doing anything to Silver St. Cloud or Vickie Vale would be cheating.
Well–Silver, anyway. Nobody cares what happens to Vickie.
The only one of Green Lantern’s enemies who know is Sinestro. And he’d kill them in a heartbeat to mess up Jordan. A nasty fellow. Only if it fit into his plans, though. He’s practical.
In Marvel…I really don’t know if Baron Zemo would go after any family or friends Captain America had if he knew his real name.
The Kingpin might be trustworthy with the ID if he gave his word, or at least he’d restrict his acts to the hero and not his family. He’d find the murder of an opponent’s family very distasteful.
In my opinion there’s fewer “civilized” bad guys in Marvel than DC.
GL’s friends are mostly super-heroes, of course. And attacking Carol Ferris is best not done casually. I can easily see Sinestro deciding that, though he’d probably be able to take Carol in a sneak attack, the not-zero odds of awakening Star Sapphire make the proposition pointlessly risky.
And most of Cap’s friends & girlfriends are super-heroes or SHIELD agents, or both. Zemo’s not going after, say, Natasha Romanov just to fuck with Cap, because it’s a guarantee of escalation. Killing Natasha is going to bring in SHIELD, the Avengers, Hawkeye, and Daredevil in addition to Rogers.
I think that would depend. Most heroes Fisk isn’t going to deal with anyway, because they’re out of his league and he doesn’t see a point in escalating matters. Yeah, he could off Ben Grimm’s ex-fiancee at will, but why would he want to draw the undivided attention of Ben, Johnny, and the Richards onto himself?
Didn’t he set off the Brand New Day storyline by attempting to kill Spider-Man’s family?
Heck, she’s more than welcome to know my secret identity, trustworthy or not.
(What? Fedoras are hot. Don’t look at me like that.)
I wasn’t. Or were you talking to Bane?
Vandal Savage and … Degaton? is that is name? Time travel guy? Both look at things in such a -huge- long-term way that identites, while useful, aren’t something they’d wave over someone’s head (Besides, with both of them, I seem to recall identites as something that’s just ‘too easy’ for them to find out).
Savage IS a long-thinker, but not in a way that makes it safe for him to find out your civilian ID…the first arc of the current JSA series involved him orchestrating attacks on the families of heroes - most of whom were long dead, so it wasn’t vengeance, it was cutting off legacies - he might not go after you, or your lover, or your kids…but your grandkids might not be safe.
Of course, this kind of backfired on him, as his attacks created three new heroes, Citizen Steel, the third Wildcat, and the current Mr America: Citizen Steel is the grandson of Commander Steel, who gained his powers when a group of superpowered neo-nazis attacked his family reunion, and he got covered in the blood of a metallic member of the group; Wildcat was prompted to go into heroing by Savage personally attacking him and his father (the first Wildcat); and Mr A was a friend of the prior one (a descendant of the original) and took up the name after he was killed.
Since Carmen Sandiego and Hannibal Lector, both non-comicbook characters have been mentioned, I’d add “Gentleman” Johnnie Marcone of the Harry Dresden stories. As long as the family/friends in question were noncombatants, at least. He’s big on sparing noncombatants from the crossfire.
The Joker has expressed disinterest in Batman’s secret identity a few times before. In Grant Morrison’s Arkham Asylum: A Serious House on Serious Earth, Batman is captured and an inmate wants to see his real face, but the Joker tells him something like “Don’t be ridiculous. That is his real face.”
Ok, that’s hysterical. 
I’m pretty sure that was my sister.