Some fans of Iron Man have called for the revival of the superhero from the Marvel Cinematic Universe (MCU), after a photo went viral this week on social media in the United States.

The move came on the eve of the second anniversary of the release of Avengers: Endgame (2019), which saw Iron Man/Tony Stark, played by American actor Robert Downey Jr, dying at the end of the movie.

The message on the billboard in Los Angeles read: "For Our Beloved Hero, Please Bring Back Tony Stark", with the billboard using the hashtag #BringBackTonyStarkToLife.

The large board also included the date 04-24-21, likely referring to the second anniversary of the movie's release in other countries after its world premiere at the Los Angeles Convention Centre on April 22, 2019.

Near the end of Avengers: Endgame, Iron Man snapped his fingers and turned the villain Thanos and his army into dust, saving the entire universe but getting himself killed due to the Infinity Stones.

His heroic sacrifice also marked the end of Downey Jr's last major outing in the MCU. He first played the character in Iron Man (2008).

However, the character did appear in Spider-Man: Far From Home (2019), the last movie in Phase Three of the MCU, through the use of archival footage from other movies.

In phase four, Marvel Studios has launched television mini-series such as WandaVision (2021) and The Falcon And The Winter Soldier (2021).

It will also soon release the repeatedly delayed movie Black Widow, starring Scarlett Johansson.

Downey Jr, 56, has said in past interviews he was done after playing the character for more than 10 years, but there may a sliver of hope for the Iron Man fans.

Black Widow also died in Avengers: Endgame, but this standalone movie is set before her death and after the events of Captain America: Civil War (2016).

There are rumours that Iron Man will make a cameo in Black Widow.