Maul: Shadow Lord is one of the best new additions to Star Wars canon. The show is being hailed for its gritty realism, gorgeous animation, and flawless sound design. The voice-over work by Sam Witwer is brilliant, as always, and the soundtrack by the Kiners is masterful. While Maul is intriguing on his own, the new characters, like Devon Izara and Brander Lawson, have been just as delightful to watch. With that said, Maul has an extremely complicated history, and he has run into nearly every major character in the Star Wars saga.
The show has made a strong impression so far, but there's nothing like fan service to really get the fandom buzzing. These characters can be shown in flashbacks, as holograms, or make a surprise appearance in the show's timeline. Here are a few character cameos that would shock everyone. PS - If you're not into fan service, this list may not be for you.

1. Ahsoka Tano
Maul and Ahsoka already had their duel in The Clone Wars season 7, so there's no chance of a rematch. Ahsoka is in hiding in this part of the timeline, with Darth Vader's Inquisitors on the loose, looking specifically for survivors of the Jedi Purge, including her.
That doesn't mean Dave Filoni's favorite character can't appear in the series. Ahsoka can be shown in a flashback of Maul's stint on Mandalore or as a hologram. You can't put it past Filoni to creatively and seamlessly include Tano and make it memorable. It would also be a nice touch with Ahsoka season 2, due out later this year.

2. Emperor Palpatine
It's impossible to imagine a Star Wars show set during the Empire's reign that doesn't include an appearance by the devil himself. Palpatine was last seen in The Bad Batch, but his betrayal of Maul looms large over Shadow Lord's narrative. Maul's desire for revenge on his former Master drives him; Palpatine doesn't have to appear in person to make an impact. A hologram would be enough to drive Maul insane and get a reaction out of him.
Still, if Sidious happens to mock Maul's failures and claim that he lets him live because his crime syndicate provides a good cover for the Empire's expansion, it would surely leave him reeling.

3. Darth Vader
Palpatine's right-hand man will probably hear about the lawlessness on Janix, and the final few minutes of Maul: Shadow Lord episode 4 confirmed that the Empire has arrived. There has never been a confrontation between Vader and Maul in canon, but if everything leads to a duel between these two dark side users, the internet is sure to break.
Maul has been portrayed as a horror movie villain in the show so far, but as the Grand Inquisitor once told Kanan Jarrus, there are far scarier things in the galaxy. Maybe Darth Vader would finally be the guy to scare Maul.

4. Bo-Katan Kryze
Bo-Katan Kryze has a shady past, and she indirectly helped Maul overthrow her sister, the Duchess Satine Kryze, on Mandalore. Eventually, Maul assassinated Satine to avenge himself on his arch-nemesis, Obi-Wan Kenobi. Maul's actions directly impacted Bo, and if she and Maul face off in the series, it may help her redemption in The Mandalorian season 3 seem more convincing. Bo-Katan would be a good fit for Maul: Shadow Lord's storyline.

5. Quinlan Vos
While Maul tries to groom Devon Izara to be his apprentice, Quinlan Vos, who started 'The Path', would be someone who could help Devon and her Master find a haven within the galaxy. Vos's work after the fall of the Republic was to take surviving force-sensitive beings to safety.
His work was explored a bit in Obi-Wan Kenobi and later on, in Tales of the Underworld. Vos was always slightly unconventional as a Jedi, but he's the type of character who could stand his own against a master manipulator like Maul. It would be great to catch up with Vos on Maul: Shadow Lord.
Maul - Shadow Lord is streaming on Disney+.
