Was there ever a superhero whose identity was never revealed (except to readers)?

Not to mention his non-canonical series. By the end of the first arc a lot of people know, including his superior at the FBI.

Plas? The Martian Manhunter? I think you may be dating yourself, but it don’t matter, I’m IN LOVE!

Mr Gravemold was one of his names.

From the same series, no one knew who the Astronomer was originally, including himself; he burned out his own pre-powers memory.

None of them seem to know the whole story, though. Even Etrigan, whose rhyming poem about the Stranger amuses me greatly, was dismissed by the Stranger as telling a distorted version of the story.

Certainly, some entities do know the person that he was - he comments during the Spiritual Crisis thing, about dying angels - that some of them knew him when he had a name, implying that they’re very old. I don’t think that disqualifies the Stranger, though - as having the direct servants of an omniscient power know your name is hardly a unique condition.

To put it another way - we’d have to disqualify the entire Marvel Universe automatically, because of Uatu.

I don’t believe anyone knew the identity of The Shadow, including the readers for a long time. I’m refering here to Maxwell Grant’s stories, not the radio series. So it was not Lamont Cranston.

What was the Shroud’s name? Was it ever given?

Wallwalker, Black Shadow, and Mr. Gravemold.

While we’re on that line, I think that later in the series, Jube is probably the only one who can keep track of Croyd’s ever-changing identity (and then only because Croyd keeps buying his papers there when he wakes up).

Does anyone ever learn who Mod Man’s creator is? I forget.

You mean Kent Allard? The real Lamont Cranston knew it, since the Shadow had his permission to pose as him.

We learn, but I don’t remember the name. He’s an utter jerk; that I remember.

I remember the origin story quite clearly. Colt “dies”, Dolan is devastated, Colt climbs in through the window and explains that he’s going to stay “dead”, put on a mask and become the Spirit. Dolan knew all the time.

Ellen did. She even called him “Denny Colt” in one of the later stories.

There was a one-off character called The Defender who was murdered by gangsters in the 40s (as shown in a recent Daredevil story). No one seemed to know or care who he really was.

She wasn’t alone, either – Sand Saref clocked him straight away: “Don’t be coy with me, Spirit. All these years and a mask don’t fool me… Denny Colt!
(From “Bring in Sand Saref,” Jan 15, 1950)

Black Orchid never seemed to have a secret identity, at least not a permanent one, that could be exposed. She was Black Orchid first, and adopted secret civilian identities on a pro temp basis - a new identity in each new story.

Maxim Travnicek, since I have some of the books above my computer right now. And yeah, he’s a jerk. He pulls a Joker in the Typhoid Croyd incident and gets more or less written out of the storyline, but I forget if anyone besides Mod Man ever really knows who he is (don’t have that book handy).

Neil Gaiman’s mini-series cemented a lot of her origin along with most of DC’s plant-based characters, tho.