Star Wars creator George Lucas entertained the idea of a major twist involving Darth Maul and General Grievous in the prequel era, but his idea would have had major consequences and hurt the galaxy far, far away. In the Star Wars canon, Darth Maul's time as a Sith apprentice was brought to an end by Obi-Wan Kenobi in Star Wars: Episode I – The Phantom Menace. He returned in Star Wars: The Clone Wars, and his story continued through the Dark Times of the Empire's reign. It seems Lucas originally had other plans, however.
https://screenrant.com/darth-maul-general-grievous-lucas-hurt-star-wars/