As is customary for any Star Wars movie, Solo: A Star Wars Story is riddled with references and cameos to other Star Wars movies. Some of these vary in size and recognizability, but I think that even the most casual of audience members had to have noticed the movie's biggest surprise cameo: Darth Maul. The former Sith apprentice is revealed at the end of the movie to be the actual leader of the criminal organization, Crimson Dawn, and beckons Qi'ra (Emilia Clarke) to his location. It was a big surprise for Star Wars fans, and likely an even bigger surprise for people who last saw Maul getting cut in half 19 years ago in Star Wars: Phantom Menace.
With his red skin and horns, people likely recognized Maul from his one other live action appearance as one of the coolest things about the prequel trilogy, but that just means they were probably totally lost as to how he can still be alive in Solo. Well, Star Wars is a multimedia franchise spitting out new stories every year, and it's there that Darth Maul was officially brought back to life in the animated TV show, Star Wars: The Clone Wars, thanks to his popularity and fan demand. However, Darth Maul has been on quite the journey since then, and even his inclusion here could be raising the eyebrows of fans who are in the know.
Maul's inclusion in Solo, based on when the movie takes place in the Star Wars timeline, makes sense, but it takes some serious tracing to get to that point. Let's start off with where most fans last saw Maul: Getting cut in half by a Padawan Obi-Wan Kenobi (Ewan McGregor) and falling down one of those big endless metal pits that seem to be in every building in Star Wars. However, as it is revealed in Clone Wars, Maul did not die from this wound. His hate and anger kept him alive, and he was able to use the Force to escape through an air vent, eventually landing in a trash container heading for the junkyard world of Lotho Minor.
Darth Maul spent the next several years living in the bowels of the planet and eventually his rage and grief drove him mad, forgetting all else save for his desire for vengeance against the Jedi and Obi-Wan. Mother Talzin, leader of the Nightsisters (a group of dark Force witches) and Maul's mother, learned that her son was still alive and sent his brother, Savage Opress, to find him. Savage tracks down Maul to Lotho Minor and finds his insane brother, now with robotic spider legs. Savage brings Maul back to their home planet of Dathomir, where Talzin uses dark magic to restore Darth Maul's sanity, and give him some more human-looking robot legs.
Now back to full strength, Darth Maul sets about getting his revenge against Obi-Wan and the two have a couple of clashes, with Obi-Wan winning and Maul escaping to fight another day. Wishing to gain more power, Maul begins to amass alliances within the criminal underworld, forming his own organization called the Shadow Collective and makes contact with Death Watch, a group of Mandalorian (a planet of Boba Fetts) extremists. Maul takes control of Death Watch and the entire planet of Mandalore, igniting a planet-wide civil war. This attracts the attention of Obi-Wan, who arrives to take Maul off the throne. Unfortunately for Obi-Wan, Maul comes out the winner here, killing Duchess Satine, a woman that Obi-Wan loved, right in front of him.
However, Maul's increased actions also attract the attention of his old master, Darth Sidious. The future emperor sees Maul as a "rival" and personally arrives to destroy him. Sidious, Maul, and Savage have a really awesome two-on-one fight that ends with Sidious killing Savage, and allowing Maul to escape because he still has mysterious plans for his former apprentice.
Moving in chronological order, this is the last on-screen appearance of Maul before he shows back up in Solo as leader of the Crimson Dawn. Lucasfilm has yet to reveal how he goes from A to B, but you can bet that story will be told one way or another. There are some comics and unfilmed episodes from Clone Wars that help continue Maul's tale, but they mostly detail his further battles with both the Jedi and the Sith, eventually ending in the Sith destroying the Shadow Collective and putting Maul on the run. So, at some point, Maul manages to get back on his robot feet and start a new criminal organization, but the trouble is that we already know how this story ends.
While Darth Maul's appearance in Solo would seem to signify that Lucasfilm is teeing him up for future use in a live-action format, we have actually already seen the end of Maul's story in Star Wars Rebels, the spiritual sequel to Clone Wars that takes place a few years before A New Hope. Maul resurfaces in Rebels, now as a half-insane elder and definitely not still the leader of an underworld organization. He's spent an undisclosed amount of time (likely several years) stranded on the planet Malachor looking for an ancient Sith weapon. Rescue comes in the form of Ezra Bridger, a young member of the Rebellion and Jedi-in-training who Maul manipulates into helping him find a Sith Holocron, which is basically a magic USB drive with Sith knowledge on it.
Maul would continue to have more encounters with Ezra and his friends, each time with Maul attempting to prey on Ezra to join him as his apprentice. Soon enough, Maul gets what he needs from Ezra and finally learns what he's wanted to know for so long: the location of Obi-Wan Kenobi. Maul travels to Tatooine and finally confronts an older Obi-Wan. The two have one last brief battle, with Obi-Wan ending Maul's life in a single stroke. The two share a poignant moment before Maul finally dies for real in the arms of his worst enemy.
Basically, we know the beginning, first half of the middle, and the ending of the story, but there's still a big chunk missing. Maybe Darth Maul's cameo in Solo: A Star Wars Story was just meant to be something fun for the fans, but the writers have indicated that it was meant to be more than just fan service. It seems like a safe bet that Maul's story will be told, but the jury is out if it will be as a comic, TV show, or a movie. Even if they do nothing with it, it was still pretty awesome to see Maul on the big screen again.