Thanks to their inclusion in the MCU, the Guardians of the Galaxy have gone from an obscure Marvel team to a household name. But the cosmic band of defenders has been around for decades, with the roster changing almost as often as the Avengers.

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With so many heroes who have been counted as members over the years, you would think that the Guardians of the Galaxy would have welcomed just about every cosmic hero under the Marvel banner. Yet there are some notable exemptions of deserving characters who have yet to join the team. Here are some of the most powerful cosmic Marvel heroes who were never Guardians of the Galaxy.

10 10. Howard The Duck

Howard the Duck in Guardians of the Galaxy

Howard the Duck had been a laughing stock in the comic book movie world for a number of years thanks to his terrible solo movie. However, he was still a fairly popular character from the comics. He's now on his way to a comeback with a Disney+ series.

Despite appearing in both Guardians of the Galaxy movies in small cameos, Howard has never been invited on the team. Given the more irreverent direction the team has taken, he seems like a natural fit.

9 9. Thor

Avengers: Endgame has set up the possibility that Thor might be joining the Guardians in future MCU films. That's certainly an exciting prospect with a lot of potential, but it has yet to happen in the comics. Thor has had plenty of cosmic adventures over the years and spent time with many cosmic characters, so there was opportunities for sure.

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Thor in the films has suffered great loss and seems to have turned his back on ruling Asgard. It makes more sense that this depressed version of Thor might join the Guardians but it's surprising he hasn't done the same in the comics after all these years.

8 8. Black Bolt

Black Bolt Was Exposed To The Terrigen Mists In Utero

Black Bolt is the leader of the Inhumans and remains loyal to that position, but that doesn't stop him from occasionally joining some other super-powered teams. Black Bolt is about to level cities with just the sound of his voice. He is one of the most powerful characters in the Marvel Universe, so he'd definitely be an asset to the Guardians.

Given Black Bolt's serious demeanor and self-control, he would certainly stand out among the more immature and ridiculous Guardians. But imagine the fun of seeing these characters interacting. It seems like a wasted opportunity.

7 7. Sentry

Sentry might not be one of the most well-known Marvel heroes, but he has proven his unbelievable strength numerous times in the comics. sentry is also one of Marvel's most interesting characters as he basically has the immense strength and abilities of Superman but is mentally unstable.

The character's very human mental health issues are a unique aspect of the character that makes him unpredictable. But due to his unmatched powers, he seems like he would be a shoo-in to join the cosmic team. Perhaps he seems like too much of a loose cannon.

6 6. Spectrum

Spectrum Monica Rambeau Captain Marvel

With Monica Rambeau introduced in Captain Marvel, it might not be too long before we see Spectrum show up in the MCU. Monica takes on the mantel of Captain Marvel for a time and even joins the Avengers. She later becomes her own hero, Spectrum, with much of the same cosmic powers of Captain Marvel.

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Spectrum has had many cosmic adventures of her own. Given that Carol Danvers joined the Guardians in the past, Spectrum seems like a pretty obvious choice. Maybe if she does appear in the MCU, we can see this happen on the big screen.

5 5. Mar-Vell

The original Mar-Vell might no longer be the most popular character to hold the mantel, but he is still one of the most powerful cosmic on the Marvel roster. He has been a notable hero for decades, but perhaps his popularity didn't line up with the resurgences of the Guardians.

Mar-Vell's power set makes him a formidable warrior against just about any enemy. He is also a natural leader which is something the Guardians seem to desperately need in some cases. But with Carol Danvers joining the team, he was passed over.

4 4. Hyperion

Hyperion Avengers

Hyperion is another character who could be called Marvel's version of Superman. He is an insanely overpowered being who has performed unbelievable displays of his abilities. Hyperion is the last surviving member of The Eternals and, like many of their kind, he is god-like in his abilities.

With Hyperion on their side, the Guardians would never run into trouble again. Sure, having such a powerful member of the group might take away some of the excitement but it's a wonder why they haven't asked him to join at any point. With The Eternals in the way, he might be seen in the MCU before long.

3 3. Hulk

Worldbreaker-Hulk

Hulk is one of those heroes who seems to fit in as well on earth as he does in the cosmic side of the Marvel Universe. Some of Hulk's most memorable storylines have taken place in the far reaches of the universe. And we've also seen the MCU embrace this in Thor: Ragnarok.

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With all his adventures, Hulk has still not had the chance to join in with the Guardians. Yes, he has anger issues, but so do a lot of members on that particular team. Certainly, his unstoppable strength would come in handy in a fight.

2 2. Silver Surfer

Silver Surfer Annihilation

Silver Surfer is one of the most complex and interesting heroes in the Marvel Universe. In an attempt to save his homeworld from being destroyed, he agreed to become a Herald of Galactus. This position has earned him a whole new set of powers that allow him to go toe-to-toe with even the most powerful beings.

Despite his sad origins, Silver Surfer has broken free of Galactus' control and served as a cosmic hero. He would be another very serious additions to the Guardians but a very powerful friend to have on their side.

1 1. Nova

Nova has become one of the most popular of Marvel's cosmic heroes over the years. Fans are still waiting for the day the beloved character finally joins the MCU. Serving as an intergalactic cop of sorts, many different characters have held the title, most notably Richard Rider.

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Nova has been involved in some of the biggest cosmic storylines in Marvel's history. He has even had run-ins with the Guardians on several occasions. However, he has never been made an official member of the team.