WARNING: The following article contains major spoilers for Avengers: Endgame.
Avengers: Endgame was meant to be the end for the first chapter of the Marvel Cinematic Universe. This meant that fans went into the movie knowing that they might lose one or two of their favorite characters and others might change forever. This happened for the original Avengers team alone, with two major deaths and the severe change of another character.
The biggest death was the man who started it all, Tony Stark. It was Iron Man who gave his life to save the world from Thanos. The very first MCU movie in existence was Iron Man and, while he had three huge movies on his own outside of the Avengers tales, there were many amazing Iron Man stories that will now never be told on the big screen.
10 Demon In A Bottle
The one Iron Man story that fans had been calling for since he made his first movie appearance was the classic Bob Layton and John Romita, Jr. Demon in a Bottle storyline. What was supposed to be a villain of the month story with alcohol as the bad guy ended up changing everything fans knew about the superhero and created layers to the character the remain in place to this day.
Iron Man 2 teased this story when Tony got drunk at a party and used the armor, causing a lot of damage. Rhodey showed up as War Machine and tried to stop him, and that could have led to this story, which climaxed with Rhodey taking the armor and the role of Iron Man for himself.
The Iron Man Deliverance story follows the Demon in a Bottle arc. Tony had given up his armor to Rhodey, lost his corporation to Obadiah Stane, and became homeless and lived on the streets. Tony was an alcoholic, and, in this story, he was wandering the streets in a snowstorm. While the police told him to find shelter, he refused because he was looking for a homeless woman he became friends with who was pregnant. He found her, but they couldn't find shelter. She went into labor, delivered the baby, and died during childbirth. The baby lived, but Tony also almost died and made his decision at that moment to contact Rhodey and seek help to beat his addiction.
8 Armor Wars
Armor Wars is arguably the most famous Iron Man event series of all-time and would have been perfect on the big screen, considering Tony Stark's arrogance following Civil War. Stark realizes that there are many criminals in the world who are using armor and weapons designed by Stark Technology. When he tries legally to get it returned and fails, he sets out to get it back on his own.
This puts him at odds with the U.S. government who demand that Iron Man be shut down. When Iron Man also takes out the Mandroids of S.H.I.E.L.D. and the superhero ream the Guardsmen, he puts a target on his own chest. This is a great story of Iron Man going rogue and ending up at odds with heroes and villains alike.
7 The Mask In The Iron Man
An idea that existed in the movies but only slightly saw the light of day concerned the AI of Iron Man's armor. In the movies, it was J.A.R.V.I.S., until the AI was sent into The Vision, and then Iron Man had a new AI after that. In Avengers: Age of Ultron, the MCU examined what would happen if the AI developed a mind of its own.
That was the story in The Mask in the Iron Man, but instead of Ultron (which was a Hank Pym creation in the comics), it was Iron Man's armor itself becoming sentient and deciding to take matters into its own hands—much to the horror of Tony Stark.
6 Five Nightmares
In the very first Iron Man movie, Tony Stark had to battle his father's old partner Obadiah Stane, who tried a hostile takeover. When Stane tried unsuccessfully to have Stark killed, he created his own armor and became Iron Monge—a story pulled from the pages of Iron Man comics. Stark beat him, took his company back over, and moved on. In the comics, the aftermath of the Stane conflict played out in Five Nightmares where Obadiah's son Ezekiel Stane wants revenge and uses Stark tech to create destructive weapons. This puts Iron Man up against someone using his tech who is younger and faster and the story takes the two men around the world.
5 Director of S.H.I.E.L.D.
The horrors inflicted on the world when superheroes and villains raged through the world unchecked and ended up resulting in Civil War. This put Iron Man on the side of the U.S. government in regulating heroes while Captain America led the resistance, leary of becoming government weapons.
The big difference between the comics and movies was that Thunderbolt Ross was left in charge mostly with S.H.I.E.L.D. in tatters. In the comics, Iron Man took over as the director of S.H.I.E.L.D. to make sure it remained clean—something he tragically failed to do. His reign as the director did nothing but weaken relationships between heroes even further.
4 World's Most Wanted
The world of the MCU was a politically dangerous place. Thanks to HYDRA infiltrating the U.S. government and the walls of S.H.I.E.L.D., no one could be trusted. This corruption doomed Iron Man in the comics because it wasn't HYDRA but Skrulls that infiltrated the U.S. government and S.H.I.E.L.D. When Secret Invasion ended, Norman Osborn was in charge, and Tony Stark was on the run, framed for crimes he did not commit.
With Spider-Man in the MCU, there was a chance Tony Stark could finally come face-to-face with Norman Osborn. This is something that could have played out in an amazing story since Norman and Tony had such an interesting dynamic—something that can never happen now.
3 Enter the Mandarin
The biggest complaint about Iron Man 3 is that fans were excited to see Iron Man battle his greatest foe The Mandarin on the big screen. However, Mandarin was a Red Herring, and instead, the story was an adaptation of the Extremis storyline with A.I.M. as the enemy. The man pretending to be Mandarin was a fraud. Now, with Tony Stark dead, he will never get a chance to battle Mandarin on the big screen -- something fans thought they might get to see thanks to a Marvel one-shot showing there was a real Mandarin after all. Enter the Mandarin was published in 2007 and retells the first meeting between the enemies.
2 10 Rings To Rule The World
As the title indicates, 10 Rings to Rule the World is another Mandarin story. The 10 Rings, of course, indicates the weapon that Mandarin uses, 10 individual rings infused with alien technology that each do a unique task. The great thing about Iron Man and Mandarin is that Tony is a man of science and Mandarin combines science with mysticism. That was missing completely since Mandarin in Iron Man 3 was just a radical militant. This comic has Mandarin capture a man who was disguised as Iron Man and the real Iron Man has to come to the rescue, battling the Mandarin's Death Squad in order to save the day.
If Iron Man meeting Norman Osborn was a missed opportunity in the movies, the fact that he never had a chance to go toe-to-toe with Doctor Doom is a tragedy that movie fans might never get to see now. Iron Man is easily the most popular armored hero of all time, and Doctor Doom is one of the most powerful armored villains in Marvel Comics. In Doomquest, Iron Man and Doctor Doom are transported to Camelot in the past. Iron Man battles alongside King Arthur, and Doom teams up with Morgan Le Fay as the two sides wage war. By the end, Doctor Doom and Iron Man have to team up to get back to their own time, and this is a story that will never see the light of day in an Iron Man movie now.