Hulk

Dr. Bruce Banner is a character from the Marvel Comics and a recurring character in the Marvel Cinematic Universe. After being imbued with gamma radiation, he gained a destructive alter ego, the Hulk, who would only emerge whenever Banner is angry. However, he has eventually gained control of the Hulk, and has even merged his mind with the Hulk's body to become a merged amalgamation known as Professor Hulk.

Early Life
Bruce Banner was a scientist who studied in Culver University, where he dated Betty Ross. As a successful scientist in the field of gamma radiation, he was approached by Betty's father, General Thunderbolt Ross, to do an experiment (in reality, he was testing a recreation of the Super Soldier Serum). However, the process transformed him into the Hulk. After the Hulk rampaged through the lab and injured Betty, Banner fled the scene into South America, where he lived for five years.

During this time, he was in contact with Dr. Samuel Sterns, with the two collaborating on a cure for Banner's condition, and was working at a bottle factory. One day, he cut himself while working, and his blood ended up in a bottle that was later purchased and consumed by Stan Lee. Lee's subsequent gamma poisoning led to the military hunting Banner down. Banner fled to Culver University, where he reunited with Betty, but was cut off by General Ross. While on the run, Banner discovered that Sterns had found a cure, and managed to heal himself. However, Emil Blonsky, hungry for the Hulk's power and already unstable from another version of the serum, infused himself with Banner's blood and became the Abomination. Banner resumed the Hulk's form, fought the Abomination, and fled to Canada, having finally managed to control the Hulk.

Sometime in the intervening years, he traveled to India, where he worked as a doctor.

How Thor Should Have Ended
During the credits, the Hulk appears when Superman and Batman wonder if they will always chat with other superheroes. The Hulk laments being sad before leaving the scene.

How The Avengers Should Have Ended
The Hulk is seen during the Battle of New York, where he assists Thor in fighting off the Chitauri, then beats up Loki while chanting, "Puny god!"

At the Super Café, the Hulk enjoys a bowl of shawarma. He is surprised when Superman and Batman mention the death of Agent Coulson, and is flustered when asked about stealing a motorcycle. However, the box office money the obscures the Avengers.

How The Winter Soldier Should Have Ended
Steve contacts the Hulk in an attempt to stop Alexander Pierce's plans, with the Hulk stealing a motorcycle to reach them. When Nick Fury calls off the Avengers, Steve apologetically texts the Hulk, much to his dismay.

Later, at the Super Café, the Hulk crashes into the building with Bucky. As Bucky complains, the Hulk then starts pounding him, chanting, "Not the villain!"

How The Avengers: Age of Ultron Teaser Should Have Ended
Hulk is present along with the Avengers as Ultron quotes various Disney films. He exclaims, "Cinderelly!" as Ultron quotes Cinderella.

How Age of Ultron Part 1 Should Have Ended
This HISHE marks Banner's official debut, as all of his other appearances were as the Hulk.

Banner is first seen as Ultron starts singing "I've Got No Strings" and uploads himself into several robot bodies. He later laments the loss of the internet to the point that he Hulks out and breaks out of the Avengers Tower.

How Age of Ultron Part 2 Should Have Ended
The Hulk watches in Sokovia as Magneto arrives and defeats all the Ultron drones. He later joins the Avengers at the Super Café.

Hulk Spoils Movies
During an interview with Rhodey, the Hulk accidentally spoils Infinity War. When Rhodey calls him out on it, the Hulk proceeds to spoil even more films, but Rhodey cuts him off before he could spoil Spider-Man: Homecoming.

How Thor: Ragnarok Should Have Ended
Thor mentions that he still has no idea where the Hulk is. At Sakaar, the Hulk reassures that he is fine as he relaxes with Valkyrie and the Grandmaster.

How Infinity War Should Have Ended
Banner celebrates the Avengers and Guardians' victory at the Super Café, where he reminisces of the time he and Black Widow believed they had a future together.

Avengers Endgame Alternate HISHE

Trivia

 * Unlike most versions, Banner himself isn't seen for the most part, except for in the Age of Ultron and Infinity War HISHEs.
 * As of the Avengers: Endgame HISHE, Banner has permanently become Professor Hulk.
 * Banner was portrayed in The Incredible Hulk by Edward Norton before Mark Ruffalo took over from The Avengers onward.
 * This is referenced in the Infinity War HISHE, where Tony mentions that Banner used to have a different face.