In Season 12 of Supernatural, Crowley sacrificed himself for the greater good, a characteristic unusual for him. He performed a spell that would heal the chasm between the alternate world and the real world, closing the tear/gate between the two. Working with Sam, he kept mum about the last important ingredient--a life. While it looked like Crowley was going to try to kill Lucifer with the angel blade, in the end he turned the blade on himself, by which sealing Lucifer in that world.
The King of Hell had outsmarted death before, but there was no turning into a rat this time or jumping into another body. With his farewell to the Winchesters, "Bye boys," he died to imprison Lucifer and to save the Winchesters and the world. Rarely a hero, he was able to make his final act a heroic one. However, we still really wish we could have Crowley back, and here are 10 ways that it could actually happen.
Alternate-World Crowley Exists and Comes to Help
While in this scenario it wouldn't be the Crowley that we love, it would still be a Crowley. Just like the alternate world gave us versions of Bobby and Charlie, we could also have a version of Crowley. That way, we'd have a little taste of Crowley in our life, even if it wasn't the real thing. Knowing how smart any version of Crowley could be, alternate-world Crowley might even know of a way to get real Crowley back.
Amara Brings Crowley Back
Amara, the Darkness, is fed up with her brother, Chuck/God. While she's adjusted to this world, she's clearly still frustrated by her brother. Additionally, she has a special spot for Dean. If there is one human that she's close to in any way, it's Dean. On top of that, Rowena (Crowley's mom) did once help Amara when she was injured, and Crowley did help raise her until she grew up.
All of this could result in her bringing back Crowley. After all, she did bring back Mary for Dean. She could bring back Crowley, too.
His Soul Escaped Hell When Chuck/God Left the Doors Open
This is a harder possibility since technically Crowley died in the alternate world, meaning that his soul would most likely be in that hell, not the current hell. However, we've already seen a couple of Sam and Dean's allies/friends who should have been in heaven (Kevin and Eileen) that were stuck in hell by Chuck/God.
So this could mean that Crowley is there as well. Since Chuck/God is a writer and would be likely to keep his interesting characters close, Crowley could have been there, just waiting to escape.
Lucifer Breaks Free and Brings Him Back
While these two are by no means, friends, if this is as big as a battle as it seems, Lucifer may come back into the fold. Reluctant to make nice with his neglectful dad, he may bring other potential allies to help in the final battle. We know that Lucifer also has the power to bring people back, and it could happen.
Sam Finds a Spell Rowena Had Been Working On
We know that Sam became close friends with Rowena; she was his mentor. They bonded over their shared trauma, and the Rowena of the most recent seasons was very different than past Rowena. We also know that Rowena took Crowley's final death pretty hard, even if she had wanted him dead in previous seasons.
In Season 15, we find out that Rowena had been working on a way to bring back Mary even after Mary's corporeal form had been blasted by an almost soul-less Jack. The spell was nearly finished, and Sam finished it in order to bring Eileen back to life. It could be that Rowena was also working on a way to bring her son back to life, although she no longer had his corporeal being. Rowena became quite powerful and kept journals/notes on her craft. Sam, a quick study, could finish another spell she started.
Billie and Jack Bring Him Back
At the end of Season 14, Jack is awakened from the Empty by Billie, stating that they needed to talk. As Death, Billie has a lot of power. Additionally, Jack had power that even scared Chuck/God. Season 14 suggested that the two would work together in Season 15. We could see both working together to bring back Sam and Dean's previous allies, including Crowley.
Returns as a Ghost or in a Dream
It could be that Crowley is able to return to visit Sam and Dean as a ghost or in a dream. He can help them on the supernatural plane and be their inside voice. It could be that Crowley is already there as a ghost, but he could be merely waiting for the perfect time to tell the boys. Equally possible is Crowley returning to Sam and Dean in a dream in order to help them prepare for their battle with Chuck/God. Good characters have a way of surprising their writers; Crowley is a good character and could easily surprise Chuck/God.
Gabriel Returns and Brings Crowley Back
Part of this is wishful thinking, we loved Gabriel and would love to see the better archangel back on the series. Gabriel's abilities include creating images that feel like reality. While he and Crowley seemed to die in the alternate world, we don't know that world's rules, and it is possible that the two could eventually come back--Gabriel first and then Crowley.
Additionally, we never really learned the extent of Gabriel's powers. Something tells us that he was more powerful than he showed, and that what we know about his abilities barely scratch the surface of what he could actually do.
Rowena's Soul Finds Him and They Work Together
While this one may be less likely, we wouldn't underestimate Rowena for anything. It could be that another motive of hers was to find Crowley when she sacrificed herself. It would be one way to make a better situation out of her sacrifice. Rowena is always one step ahead of almost anybody, especially and even the Winchesters.
We could see her both sacrifice herself (as she did) and attempt to find Crowley so that they both can return. Besides, holding all those dark souls might make Rowena more powerful in her death, giving her even stronger magic than when she was alive. In addition, we'd love to see mother and son together again. Beforehand, they didn't have the best relationship. However, both had changed so much by the time of their deaths that they may now have the potential to build a stronger and more caring relationship. They do have one more thing in common: their love of the Winchesters.
Became King of Hell in Alternate World, Brings Self Back
Crowley is one to make the best out of a bad situation. Although he was tired of being King of Hell in Sam and Dean's world, we could see him working his way to the top again. Figuring out the alternate world and the systems of hell there, would be like learning a foreign language to Crowley. Additionally, he could find out how to reach out to his favorite hell-hound, which could basically drag his soul back.
A resourceful character, it wouldn't surprise us if Crowley does that. We hope that is the case because it'd be great to see him back, after all who else is going to lighten the atmosphere and call Dean Squirrel and Sam Moose?