On April 5, Warner Bros. and DC Comics bring "Shazam!" to the big screen. Here is everything you need to know about the superhero once known (by his archenemy, Dr. Sivana) as "the Big Red Cheese" and to the world at large as Captain Marvel. No, not that one. We'll explain.

(Also, read our review of "Shazam!")

So who is this guy? He looks familiar but I don’t remember a superhero named Shazam.

In this new movie called "Shazam!," this character is called Shazam. He is essentially the same as a character called Captain Marvel, who dates from the late 1930s.

Wait, does this have anything to do with the Captain Marvel in the Marvel Uni—

Nope. Well ... nah, let’s stick with nope for the moment.

Well, that’s a little confusing.

Oh, just wait.

This Captain Marvel was created by an artist named Charles Clarence “C. C.” Beck and a writer named Bill Parker. He first appeared in Whiz Comics No. 2, which which was published by Fawcett Comics and sported a cover date of Feb. 1940. And, for a while there, he was more popular than Superman.

Seriously?

Yep.

Captain Marvel’s alter ego was an orphaned newsboy named Billy Batson. One day, 12-year-old Billy gets on a mysterious subway car, which leads to a mysterious cave.

Within it, he encounters an ancient wizard named Shazam, whose name is an acronym that stands for the names of one king from the Bible and five figures from Greek or Roman myth: Solomon, Hercules, Atlas, Zeus, Achilles, and Mercury.

The wizard tells Billy that the boy will receive the abilities of those legendary figures (wisdom, strength, stamina, power, courage and speed, respectively) if he says the magic word, which also happens to be the wizard’s name.

Billy does so; is hit with a bolt of magic lightning; and is transformed in a tall, muscular, slightly squinty adult in a really cool red, white and gold costume (whose face is allegedly based loosely on that of movie idol Fred MacMurray).

» RELATED: ‘Game of Thrones,’ ‘The Twilight Zone’ and BTS: A guide to pop culture in April

When he says the word again, he changes back to Billy Batson (who gets a job as a radio reporter on WHIZ, because 1940s comics orphans had an awful lot of freedom).

Which is to say that Captain Marvel’s origin story is perhaps the all-time greatest wish fulfillment tale in a genre that contains thousands.

Wow. That’s pretty genius. What did the kids who read comics think?

First, it’s important to remember that superhero comics as we understand them had only existed for less that two years at that point. Superman had only been around since 1938, Batman since 1939. These were not established properties but still essentially experiments in publishing. Fawcett Publications started a comic book line in 1939. This becomes important a little later.

Second, heck yeah, the kids loved him. Written by Otto Binder after Parker headed off to war, Captain Marvel stories were often whimsical, funny and adventurous all at once. Fawcett soon spun off a Marvel Family: Mary Marvel, who was Billy’s lost sister! Captain Marvel Jr., who was their friend, Freddy Freeman! (He got his powers when he yelled "Captain Marvel!," so he essentially couldn't say his own name without transforming.) Uncle Marvel, an overweight, middle-aged guy! The Lieutenants Marvel, who were three other boys also named Billy Batson somehow! A talking tiger named Mr. Talky Tawny!

(Golden Age comics are amazing, y’all.)

Titles in which Captain Marvel appeared (including Whiz and Captain Marvel Adventures, among others) sold in the millions. At one point, Captain Marvel Adventures was published bi-weekly and sold a total of 14 million copies in 1944.

The peak of Captain Marvel might have been a storyline called “Captain Marvel and the Monster Society of Evil,” a 24-chapter serial that pits Marvel against a plethora of amazing bad guys. Collected just once, it is likely never to see the light of day again, filled as it is with unfortunate racial stereotypes, common in their day, of both African-Americans and East Asians. It’s a great story, but that stuff is inexcusable.

Captain Marvel inspired a film serial in 1941 and a radio show in 1943. An artist named Mac Raboy drew Captain Marvel Jr. in a much more realistic, illustrative style than C.C. Beck’s cartoonish mode. Junior was the favorite superhero of a young man named Elvis Presley, who styled his 1970s jumpsuits after the teen hero’s outfits — short cape and everything. The lightning bolt on Elvis’s "TCB" logo is straight out of Captain Marvel, as well.

In sum, during the first half of the 1940s, Captain Marvel was about as popular as it was possible for a superhero to be.

Then what happened?

DC Comics (then still called National Periodical Publications) happened.

They had always been a little salty about Captain Marvel seeming to be a Superman rip-off. They first sued in 1941 and went to trial in 1948. There was a decision in Fawcett’s favor in 1951, which DC appealed. In 1952, DC scored a partial victory, and the case was sent back to a lower court. Fawcett settled out of court. It didn’t help that superheroes were a bit of a fad in the early days, and Captain Marvel’s popularity had dropped like a rock after the war. Fawcett folded the comics line in 1953.

Here is where it gets really weird: In the 1950s, a British comics publisher, which had been publishing Captain Marvel reprints, started publishing a book called Marvelman, which was basically Captain Marvel with the serial numbers filed off (Marvelman! Young Marvelman! Kid Marvelman!). This lasted until 1963.

What does the Marvelman thing have to do with the price of fish?

Just hold your water, this becomes more important later.

Lord, there’s more?

By the 1960s, when Marvel Comics (of all names; no relation) brought superheroes in general back from the dead, Fawcett was, thanks to their settlement with DC, forbidden from publishing Captain Marvel. DC, in a somewhat cynical victory lap, licensed the Marvel family from Fawcett and folded them into what DC calls its multiverse: a grand cosmology containing the heroes you know and alternate worlds where strange adventures, sometimes starring analogues of those heroes, occur. They were even given their own world, called Earth-S.

» RELATED: The 5 most ′ Matthew McConaughey’ Matthew McConaughey performances

But Marvel Comics' power was such that Captain Marvel couldn’t be published under that name, so the new comics were called Shazam! By 1974, a new generation of kids thought the character’s name was Shazam, even though the character was still called Captain Marvel in the stories.

He was even on TV in a rather odd live-action TV show called "Shazam!" in which a teenage Billy Batson traveled around in a van with an old man named Mentor having very simple adventures.

... what?

It was the 1970s. I don't know what to tell you.

To make everything that much more complicated, Marvel Comics created a character called Captain Marvel in 1967, an alien warrior upon whom the 2019 “Captain Marvel” movie is based.

Okay, that one I know.

Yeah, that has turned out to be a pretty popular movie.

By the end of the 1970s, the revived Captain Marvel/Shazam had proven a bit of a bust. The character didn’t quite work in a modern context. Talking tigers, and whatnot.

Captain Marvel and the Marvel family became total B-list characters and were eventually fully integrated into the DC Universe as standard-issue superheroes. Various revivals and reboots were attempted over the years. None ever really stuck or contained much of the charm of the 1940s adventures.

You said something about Marvelman becoming important again.

Yes, Marvelman.

In 1982, a young, up-and-coming comics writer named Alan Moore revived the character (which was published under the name Miracleman in the U.S.).

This was one of the very first dark/“grim and gritty” takes on an old character. In Moore’s excellent (if somewhat dated) run, Miracleman’s alter ego is a pudgy, middle-aged guy with awful headaches; Miracleman becomes a god; and Kid Miracleman becomes a demonic figure prone to mass murder.

The final battle between them, in Miracleman No. 15, is one of the most violent comic books ever published. Zack Snyder has probably read it more than a few times.

Ever since Miracleman, which began Moore’s run as perhaps the most influential mainstream comics writer of his era, attempts to modernize the once-sunny Captain Marvel have felt vaguely skeezy and off-putting.

In Alex Ross and Mark Waid’s 1990s mini-series “Kingdom Come," Captain Marvel is a brainwashed bad guy. In Grant Morrison's late-2000s crossover event "Final Crisis," Mary Marvel turns evil, which you can tell by her black leather outfit and pink hair.

Most recently, DC rebooted the Marvel family to make the supporting cast a bit more diverse — Eugene Choi, Pedro Peña and Darla Dudley, who all show up in the new movie.

In 2012, DC finally straight-up renamed the character Shazam, which is why the movie is called "Shazam!" and not "Captain Marvel" (among other, Brie Larson-related reasons).

... you done?

Yeah, I think so. My point with all this is two-fold.

First, the story of Captain Marvel/Shazam is the story of just how knotty and complicated the ethics surrounding corporate-owned comics can be.

The Superman character was created by Jerry Siegel and Joe Shuster, the copyright to which they sold to National for a song. National created nothing, but they owned the intellectual property that was Superman, so they sued Fawcett when Captain Marvel got popular, which likely helped Fawcett go out of business.

Did Jerry Siegel and Joe Shuster see any money from Captain Marvel? Of course not.

Did Marvel Comics essentially forbid DC from using the correct name of a character that existed long before the company that created Spider-Man did? Absolutely.

Second, it's a little ironic that the character has come full circle, at least in the movies. With movies such as "Batman v Superman: Dawn of Justice" and "Suicide Squad" being so dark, the movie version of Captain, uh, Shazam has gone in the other direction. The film seems to be more like the hero's 1940s incarnation than, say, the movie version of Superman seems like the comic book character.