Orko can't be overlooked. Despite being a bit of a comical character, he has his own charm. Fanfictions sometimes focus on his magic abilities, which are often a bit unreliable, and how he uses them (or tries to use them) to help the heroes. His homesickness for his own planet is also a topic that some fanfictions explore, adding a touch of depth to his character.
Teela is quite popular too. As a strong female character, she offers a different perspective in the fanfictions. Writers often explore her relationship with other characters, her training as a warrior, and her role in protecting Eternia. Another popular character is Man - At - Arms. His knowledge of weapons and technology in the Masters of the Universe world is often used in fanfictions, whether it's creating new weapons for He - Man or coming up with strategies to defeat the villains.
He - Man is obviously one of the most popular. He's the main hero, so many fanfictions revolve around his adventures, his battles against Skeletor, and his growth as a character. Skeletor is also very popular. His evil nature and his constant scheming make for great plotlines. People like to write about his attempts to take over Castle Grayskull and his interactions with his minions.
Hermione Granger is extremely popular. Writers often like to explore her intelligence further, perhaps in a scenario where she discovers a new branch of magic through her extensive research. Her relationship with Ron or Harry can also be delved into more deeply in fanfiction.
Jason Grace is a character that features a lot in fanfiction. His leadership skills and his connection to the Roman side of the demigod world are interesting aspects to write about. Fanfiction writers may explore his relationship with Percy, especially how they combine their different leadership styles when facing challenges together, and his struggle to adapt to the Greek demigod world after being brought to Camp Half - Blood.
Hit is quite popular. His time - skip ability makes for some really interesting fight scenes and plot twists. Writers can explore his backstory more, like his training and how he developed such a unique power.
Hayato Gokudera is quite popular. In an alternate universe, he might be a lone samurai in a feudal Japan - like setting, or a tech - genius hacker in a cyberpunk world. Then there's Yamamoto. He could be a star athlete in a world where sports are the main focus instead of Mafia activities. His natural athleticism and positive attitude would make him a great character to develop in such a setting. Also, Hibari is often chosen. He could be the strict headmaster of a strict academy in an alternate educational - themed universe.
Teela is also quite popular. She's a strong female character, and in fanfiction, she can be explored further in terms of her own story arcs, her feelings for He - Man, and her development as a warrior. Man - At - Arms is another one. His role as a mentor - like figure and his knowledge of technology in Eternia can be the focus of interesting fanfictions.
Sakura is also quite popular. Fanfiction often focuses on her development as a kunoichi, her relationships with Naruto and Sasuke, and how she overcomes her insecurities. There are many stories that give her more agency and power than in the original series.
Dr. Colosso, the family's pet bunny who is actually a supervillain, is another popular character. Fanfiction might explore his backstory more deeply or have him team up with other villains in a plot to finally defeat the Thunderman family.
JD Fenix is also quite popular. As Marcus's son, he has his own story arc in Gears 5 that can be expanded upon in fanfiction. You can explore his relationships with other characters more deeply, like his friendship or rivalry with other soldiers. Del Walker is another character that fans like to feature. His unique personality and his role in the team can lead to some interesting fanfic stories.
Jareth is by far one of the most popular characters. His mysterious and powerful nature makes him a fascinating subject. Writers can explore his backstory, his relationship with the Labyrinth, and his complex emotions.
Neo is definitely one of the most popular. His journey as 'The One' offers a lot of scope for further exploration. Writers can continue his story after the events of the movies, or even rewrite parts of it. Trinity is also very popular as she is a strong female character. Fanfiction might explore her past more or create new adventures for her. Morpheus is another favorite, with his wisdom and leadership being great elements to build stories around.