If there is one thing fans learned about superhero stories, it is that death is not always permanent. The Marvel Cinematic Universe (MCU), for instance, has brought supposedly dead characters back to life for a few times now, and it looks like it will be doing it again in "Avengers 4."

A new report reveals that Brock Rumlow aka Crossbones (Frank Grillo) may be back on his feet during "Avengers 4." There is no photo to back up this rumor, so it is best to take it with a grain of salt. However, a Redditor who posts behind-the-scenes photos and claims to be an extra in the upcoming film said they saw the "guy who plays Crossbones" on set.

Grillo's character was seemingly killed in the opening act of "Captain America: Civil War" when Scarlet Witch (Elizabeth Olsen) contained and detonated a bomb explosion meant for Cap (Chris Evans) near the former HYDRA agent. Assuming the rumor of his return is accurate, Cinemablend says there are only two options on how Crossbones will play into "Avengers 4."

If he survived the explosion in "Civil War," the publication suggests he would be part of a side narrative. However, considering his previous situation makes it difficult to bring him back, it is also possible for Crossbones to appear only in a flashback. Recent "Avengers 4" set photos hint there will be flashback scenes, after all.

Plus, Grillo has once hinted that the MCU is not done yet with his character. It's just that the studio still has no idea what to do with the villain. Although he did retract his statement shortly after, it is not far-fetched to see the character back.

The studio has a reputation for resurrecting "dead" characters. Agent Phil Coulson (Clark Gregg), for one, who was stabbed by Loki (Tom Hiddleston) in the first "Avengers" film, was brought back to life in "Agents of S.H.I.E.L.D." Captain Rogers' good old friend Bucky Barnes also died in "Captain America: The Winter Soldier," only to be revived in the sequel. Then, there's Loki in "Thor: The Dark World" and Groot (Vin Diesel) in "Guardians of the Galaxy" who are very now much alive to return for "Avengers 4."

Plot details are currently under wraps, but there is a rumor that Thanos will be resurrecting deceased characters to help him in his fight against Earth's mightiest heroes. If Crossbones indeed returns, there is a good chance he will be part of the Mad Titan's army.

"Avengers 4" will be released in theaters on May 3, 2019.