Through Phase One of the Marvel Cinematic Universe, Clark Gregg’s Phil Coulson was the uniting force of the films and quickly became a fan favorite. He was so popular, the character was brought back for Marvel’s Agents of S.H.I.E.L.D.

RELATED: Why Agents of SHIELD's New Threat is Targeting Fitz

For five seasons we got to see Coulson build his team into a family and save the world several times over. At the end of the fifth season he succumbed to his injuries from The Avengers while in Tahiti with May. Season six saw Gregg return as Sarge, sparking fan theories ranging from plausible to ridiculous. We’re taking a look at some of the most interesting guesses about Agents of S.H.I.E.L.D.’S Sarge.

10 COULSON IS REALLY A WATCHER

This theory from Reddit user u/RagglenLove puts forth the idea that Coulson works with the immortal watchers. After joining S.H.I.E.L.D., he faked his death in The Avengers, so the team would have something to fight for. This would lead to him working for them in a new capacity as Sarge.

Since this ruins almost every storyline from the series we can’t see the writers going with this one. We also know that the MCU has already used this gimmick to explain all Stan Lee’s cameos, so they’re not likely to use it again for Coulson.

9 HE’S A SKRULL IMPOSTER

Yes, Sarge as a rogue Skrull is the most unlikely explanation. Even Clark Gregg has debunked this theory while promoting season six. There’s just one problem, in order to hide a huge plot twist, Marvel has been known to mislead fans in the past.

So far we haven’t seen Sarge use any abilities that would indicate he’s a Skrull, but we’re only a few episodes in, and we’ve already seen at least one Coulson Skrull in the MCU. It’s a longshot, but we don’t feel we can completely rule it out yet.

8 HE HAS AMNESIA

At their core, comic books are basically soap operas with superheroes, so why not use one of soaps most classic tropes by giving Coulson amnesia? With all the space and time travel S.H.I.E.L.D. has been up to over the years, we can easily imagine a world where this Coulson was resurrected without his memories.

RELATED: Spider-Man: Far From Home Legitimizes Every Marvel TV Show

This could set up some great work from Clark Gregg when the good guy remembers all the bad things he’s done as Sarge. Considering all the cosmic and magical shenanigans the team has been involved in, amnesia would be the most down to Earth situation for them to deal with.

7 IT’S COULSON FROM THE FUTURE

Season five revolved around the team trying to get back to their own time and stop the Earth from being destroyed. It was clear from the first episode that this was a much darker future than anyone imagined.

Perhaps an abandoned Coulson from this future broke bad and discovered much more permanent ways of saving planets.The only thing holding us back from this one is that we don’t think Coulson would knowingly go to the dark side.

6 POST-SNAP COULSON

Agents of S.H.I.E.L.D. has made a conscious effort to ignore Thanos’ snap. It’s frustrating sure, but maybe they aren’t really ignoring it, just saving it for later in the season. Avengers: Endgame featured Hulk using the Infinity Gauntlet to bring back everyone Thanos snapped.

If this somehow included Coulson, perhaps he came back wrong? He could be a version of Coulson where something went wrong because of all his contact with aliens. Literally, anything is possible if the Infinity Stones are involved.

5 HE’S FROM A MIRROR UNIVERSE

One of the most intriguing theories we discovered posits that Sarge is from the MCU version of a Mirror Universe. Made famous in the Star Trek franchise, it features evil versions of the regular characters. With his team and the way he goes about completing missions, Sarge does have some very distinct Coulson qualities, only he’s a bad guy.

RELATED: Agents of SHIELD Showrunner Steps Into Season 6 Role

At this point, Agents of S.H.I.E.L.D. has exhausted almost every possible wild comic book story, so a Mirror Universe would be something new. It also opens up the entire MCU to new character possibilities.

4 HE’S AN EVIL LMD

Once they decided that it was actually Coulson May saw come through the portal, she and Mack’s first guess was an evil Life Model Decoy. Considering what they went through with Radcliffe and Aida, it’s no surprise that was their immediate response.

While in the world Aida created they thought everything was real and had new lives with new experiences. It’s possible that Sarge is the evil LMD of Coulson somewhere in space and time. Though Fitz is missing and Radcliffe is gone, we know someone, somewhere got a hold of their work, because that’s how comic books work.

3 ALIEN CLONE

Phil Coulson’s Agents of S.H.I.E.L.D. story started with him being saved through an alien blood transfusion. We later found out it was a Kree whose blood was used, with Coulson exhibiting strange psychological effects from the process. As the MCU has developed we’ve discovered that the Kree are not the good guys they pretend to be, meaning their blood could have done something extra.

This is only the most direct contact Coulson has had with aliens. Throughout his career he has fought for and against so many aliens and Inhumans that it’s not a stretch to think one of them acquired enough of his DNA to make a clone.

2 TIME TRAVEL CREATION

Throughout the MCU we’ve been told over and over how fragile time is. Usually, this is right before someone travels through time. No one has broken the rules of time more than Coulson’s S.H.I.E.L.D. team. Season five saw them relive the destruction of the Earth several times so they could figure out how to stop it.

Knowing how delicate time is, it wouldn’t surprise us if somewhere along the way a clone or duplicate was created. This isn’t a new concept, but it would be a very logical way to explain Sarge’s familiarity with Coulson while maintaining a more brutal way of life.

1 ALTERNATE EARTH DOPPELGANGER

We guessed early in season six that Sarge and his team were not from this Earth. They have little sympathy for Earth or its people and only care about completing their mission. S.H.I.E.L.D. scientist Marcus Benson confirmed that Sarge’s DNA matched Coulson’s and that they likely destroyed the last planet they came from.

With Spider-Man: Far From Home teasing the introduction of the multiverse to the MCU, Agents of S.H.I.E.L.D. could be following suit. We’re thinking Sarge is from another Earth that didn’t survive the many catastrophes S.H.I.E.L.D. and The Avengers have prevented.

NEXT: Agents of SHIELD Season 6 Character Has a Hulk Connection