How much money is “Avengers: Endgame” going to make? All of it.

The Marvel Cinematic Universe (21 films, $18 billion and counting) is the highest-grossing franchise in movie history.

Three previous Avengers movies combined to make almost $5 billion. “Avengers: Endgame,” scheduled for a Friday, April 26, release, is the follow-up to “Avengers: Infinity War,” which generated more than $2 billion worldwide and is the fourth-highest grossing film of all time.

Seven of the 20 highest-grossing films of all time are based on characters in Marvel or DC comic books. Ten movies about Marvel and DC characters have made at least a billion dollars. Superheroes have become the most bank-able stars in Hollywood.

How did we get to this point? Let’s retrace 15 steps.

1. Sunday funnies

In the era before comic books, there were comic strips. Harry Wildenberg and Maxwell Gaines partnered in the 1930s to invent what is acknowledged as the first American comic book. They accumulated material from comic strips and packaged it in a comic book format as Famous Funnies. If you wanted comic strips without all that bothersome news that might be found in a newspaper, you could snare Famous Funnies for a dime. The first monthly issue of Famous Funnies debuted in 1934.

Famous Funnies became a cash cow, so you know what happened next: Other publishers jumped on the bandwagon. Reprints of comic strips gave way to original characters and stories.

2. Birth of superheroes

Superman’s 1938 arrival in Action Comics No. 1 paved the way for a flood of superheroes. Batman, inspired by pulp heroes, came along in 1939. So did Marvel’s first superhero. The Sub-Mariner (he still hasn’t shown up in a movie) and his “frenemy,” the Human Torch, debuted in Marvel Comics No. 1. Captain America was introduced a year before the U.S. entered World War II, but the cover of Captain America Comics No. 1 depicted the hero punching Adolf Hitler.

3. Superman conquers another medium

Even before Superman graduated from Action Comics to his own title, a Superman radio series was sold to radio stations. Scripts were read by local actors for local audiences. That led to “The Adventures of Superman,” a syndicated radio show that aired from 1940 until 1951. Bud Collyer, the first host of the game shows “Beat the Clock” and “To Tell the Truth,” voiced Superman. The radio show introduced kryptonite and the phrase “up, up and away” to Superman mythology.

4. Capes reach big screen

The first comic book superhero to reach theater screens wasn’t Superman. It was the original Captain Marvel, now referred to as Shazam. “The Adventures of Captain Marvel,” starring Western actor Tom Tyler, was a 1941 movie serial. Later that year, the first of Max Fleischer’s still-revered Superman cartoons debuted.

Batman (1943), Captain America (1944) and a DC Western hero, Vigilante (1947), were showcased in movie serials before Superman, who was portrayed by Kirk Alyn in a 1948 serial. A second serial (“Atom Man vs. Superman”) appeared in 1950, and George Reeves starred as Superman in a 1951 feature film, “Superman and the Mole Men.” And the Reeves movie led to ...

5. Capes reach small screen

Reeves played the title role in a Superman TV series (“The Adventures of Superman”) from 1952-58. Did the TV program lead to a proliferation of other comic book-inspired TV shows on the airwaves? Nope. A villain in the “real world” was mounting a crusade against comic books.

6. ‘Seduction of the Innocent’

Kids weren’t the only folks reading comics after World War II. They were popular with those who served the country, too. There were so many consumers of the cheap form of entertainment that, in 1949, the combined annual sales of the top 10 publishers was $340 million annually, according to the Ron Goulart book “Great American Comic Books.”

The content in comic books “grew up,” too. Boundaries were pushed, especially in the genres of horror and crime comics.

Comics came under attack. Bonfires were staged to burn comics that were considered to be twisting America’s youth. A psychiatrist, Dr. Fredric Wertham, campaigned that comics undermined morals, glorified violence and were a cause of juvenile delinquency. He published a book (“Seduction of the Innocent”) about comics in 1954, the same year he testified in front of a Senate Subcommittee to Investigate Juvenile Delinquency.

Seeking to avoid regulation, comic publishers regulated themselves with the creation of the Comics Code. Content became tamer and once-popular comics like Tales from the Crypt (later mined for a successful HBO series) were driven to extinction. Comic book circulation declined. Publishers were in trouble. Endgame?

7. Heroes return

Think superheroes have always been the preferred flavor in comics? Not true. Superman and Batman have been published continuously since their creation, but superheroes fell out of favor with readers after World War II. Captain America’s title was canceled in 1949. The last two issues were titled Captain America’s Weird Tales in an attempt to capitalize on the horror craze. DC pulled the plug on many of its superhero books.

That might have been the end of the superhero era, but DC (might as well try something to spark sales?) trotted out new versions of old characters like Flash, Green Lantern and the Atom. The superhero revival attracted Marvel’s attention. Stan Lee brainstormed the creation of the Fantastic Four in 1961, Spider-Man in 1962 and a slew of other new characters who became lasting figures in pop culture.

8. Batmania

Folks who lived in the pop art era were primed and ready to embrace a colorful version of Batman in 1966. A campy TV series lasted three seasons and, in between the first and second seasons, Adam West and company appeared in Batman’s first feature film. Batman was groovy, although traditionalists balked at how far the character strayed from his dark roots.

Regardless, superheroes were cool enough to spread to other mediums again. “It’s a Bird, It’s a Plane, It’s Superman” was a Broadway play in 1966. Bob Holiday played Superman. Linda Lavin of “Alice” fame was in the cast (no, she wasn’t Lois Lane). The play closed after only 128 performances and was re-cast for a 1975 TV special.

9. Saturday morning

Marvel’s characters made the transition to animation in the second half of the 1960s. Catchy theme songs, much more than the animation, were the most memorable thing about the Marvel cartoons. Superman, Aquaman, Batman and the Super Friends popped up on Saturday mornings, too, along with a live-action version of “Shazam!” Were better TV projects around the corner?

10. Prime time

Stan Lee hit the lecture circuit at colleges after his flawed heroes gained fame in the 1960s. Some of those heroes graduated to prime-time series in the 1970s. “The Incredible Hulk” aired from 1977-82 (plus bonus TV movies). “The Amazing Spider-Man” lasted 13 episodes. A “Doctor Strange” pilot was unsuccessful.

DC’s Wonder Woman hit prime time in the ’70s, also. Cathy Lee Crosby starred in a 1974 TV movie before Lynda Carter starred in a Wonder Woman series from 1975-79. The first season was set in World War II before a shift to modern times.

11. You will believe a man can fly

Can a superhero movie be good without being cheesy? In 1978, a “Superman” motion picture starring Christopher Reeve raised the stakes for comic book films. Three sequels and a Supergirl movie followed, but the franchise ran out of gas.

A blockbuster “Batman” movie arrived in 1989 and followed a similar pattern — three sequels and let’s hang up the cape. The era of nonstop superhero films was still decades away, although DC’s Swamp Thing became a movie star in 1982 and 1989. Wes Craven, who later crafted “Nightmare on Elm Street,” directed the first installment.

12. Waiting game

Movie success eluded Marvel. “Howard the Duck” bombed in 1986. Comic readers understood Howard, but the moviegoing world wasn’t ready for a fowl so far removed from Donald. “The Punisher” (starring Dolph Lundgren) was virtually a straight-to-video flick in 1989. Two Captain America TV movies were followed by a direct-to-video feature film. A low-budget 1994 Fantastic Four movie was never released. In the meanwhile, the Teenage Mutant Ninja Turtles, inspired by an indy comic book title, starred in a 1990 box-office smash. Marvel’s luck seemed to be mirroring Peter Parker’s luck.

13. Marvel gets fangs

Blade the Vampire Slayer, a supporting character in a Marvel series titled Tomb of Dracula, gave Marvel its first box-office champ in 1998. Three “Blade” films were made starring Wesley Snipes, and they generated more than $415 million worldwide.

Amid the Blade films came the release of “X-Men,” “Spider-Man,” “Daredevil” and “Spider-Man 2,” all crafted by other studios. For longtime Spider-Man readers, it was a thrill to see the character done “right.” The unleashing of Marvel Studios was a next step.

14. DC in TV and film

Beginning with “Lois & Clark: The New Adventures of Superman” and continuing to present day, most TV series based on DC characters seem to push the right buttons, but DC’s recent movie history is marked by hits (the Dark Knight trilogy; “Wonder Woman”) and misses (“Jonah Hex”; the financially lucrative gloom-fest “Batman v. Superman”). Maybe “Shazam!” is an indication that DC has figured out moviegoers want to enjoy more than just popcorn.

15. Marvel Studios

Who knew that a guy in a suit of armor was going to be the cornerstone for a movie dynasty? Released in 2008 by Marvel Studios, “Iron Man” was a critical and financial success. Robert Downey Jr. was perfect for the role of Tony Stark, and “Iron Man” was the launch pad for all the movies that make up the tapestry between then and “Avengers: Endgame.” What happens after Thanos’ finger snap? It’s likely a $2 billion question.

Jimmie Tramel 918-581-8389

Twitter: @JimmieTramel

Scene Writer

Jimmie is a pop culture and feature writer at the Tulsa World. A former Oklahoma sports writer of the year, he has written books about former Oklahoma football coach Barry Switzer and former Oklahoma State football coach Pat Jones. Phone: 918-581-8389