The Iron Man revelation in 'Avengers: Endgame' has heartbroken fans tweeting 'I love you 3,000'

• Marvel's "Avengers: Endgame" is finally in theaters after its devastating sequel "Avengers: Infinity War" left fans reeling.
• Warning: There are major spoilers ahead for "Avengers: Endgame." Do not read ahead if you haven't seen the movie.
• Many people were worried that beloved characters could die.
• The Iron Man revelation sent Twitter into a spin, with many using his now-iconic line "I love you 3,000" to cope.
• Visit INSIDER's homepage for more stories.

11 years before "Avengers: Endgame," Tony Stark was the first Avenger that audiences met in 2008, captivating fans with his playboy persona and affluent attitude.

Since many have an emotional attachment to him, some fans were particularly nervous they'd be saying goodbye to Stark, aka Iron Man, in "Avengers: Endgame."

Unfortunately, they were right. Iron Man, played Robert Downey Jr., sacrificed himself in order to save the universe at the end of the film. He uses all the Infinity Stones to orchestrate the demise of Thanos (Josh Brolin) and his army, but exerts so much energy that he can no longer live.

The film concludes at Stark's funeral, and Captain America (Chris Evans) returns all the Infinity Stones to their rightful order in the timeline where the Avengers swiped them from. It appears that nobody will be using the stones to bring Stark back to life. The man who started it all is hanging up his iron armor for good, a bittersweet way to bid adieu to one of MCU's most beloved characters. 

Naturally, Twitter users were overcome with emotion over the death of one of their beloved superheroes.

Some people reminisced to the first time they saw anything with Iron Man on the big screen

In a particularly emotional nod, fans used a now-iconic line from the movie to say goodbye: 'I love you 3,000'

In the film, Stark tells his daughter Morgan that he loves her to infinity and she responds, "I love you 3,000," a line he repeats in his goodbye video he recorded before his death near the end of the film.

Fans borrowed the phrase to say goodbye to their favorite superhero.

Marvel Studios sent the message right back to fans. 

Fans noticed the end credits of "Avengers: Endgame" appear to have one final nod to the iconic character

"After the fourth phase of credits, a simple Marvel logo appears on screen," Twitter user Vichy Goodwin wrote. "It's accompanied by a sharp, repeating noise — metal bashing against metal. It's the sound of Tony Stark creating the proto-Iron Man suit, the Mark 1, in 2008's Iron Man."

A few other fans noticed the similarity between the sounds, too.

If true, it's a fitting conclusion to a franchise launched 11 years ago and a great way to say goodbye to everyone's favorite hero.

Follow INSIDER on Facebook.

Watch: The hidden meaning behind the 'Avengers: Endgame' end credits

ncG1vNJzZmivp6x7o8HSoqWeq6Oeu7S1w56pZ5ufonyiwsSnnp6qo2Kyr7DGmqSeZZaWu26%2BxJqaraGfo8BuwM5moKunnmK6orqMa2dqcV1p