General Grievous Wasn't a Sith - But He Learned Certain Skills From Them. General Grievous never became a Sith in the Star Wars Universe. But his time with them made him one of the scariest enemies in the franchise.
Grievous was never a Sith, as he was most likely a tool used by Sidious and Dooku during TCW, also Grievous was never Force-Sensitive, he's a cyborg and he just excelled in saber combat.
Grievous is a cyborg, but you can still be a Sith if you are one (Darth Vader, for example). However, that isn't the problem. Grievous was not Force-sensitive, so he cannot be a Sith. He was extremely skilled and basically a killing machine for the Separatists, yes, but he was not Force-sensitive.
The Clone Wars would later suggest that Grievous was denied the right to become a Jedi due to his lack of connection to the Force. Writers Dave Filoni and Henry Gilroy postulated that Grievous volunteered for cybernetic modifications to rival the Jedi that rejected him.
Grievous Asks Palpatine if he can be a Sith Lord - Once Upon a Theory
Why does Grievous hate Jedi so much?
Grievous utterly hates the Jedi and their evil Order for committing genocide on his people when he was a warlord. He exploited the Jedi's "compassion" for the clone troopers under their command, exemplified during his attack on the Kaliida Shoals Medical Center.
In material that is now considered Legends, Qui-Gon is even described as a Gray Jedi. Additionally, the term has also been applied to Force-sensitives who aren't affiliated with the Light or Dark side of the Force. Quite literally, these Gray Jedi don't see things in black and white, or light versus dark.
Count Dooku was a menacing Sith Lord and central figure in the Clone Wars. Once a Jedi -- trained by Yoda -- he became disillusioned with the Jedi Order and thirsted for greater power.
He developed a habit of collecting weapons as trophies from numerous enemies. Like others of his species, he became known for his lack of mercy and obsession with the glory gathered in war, valuing bravery in combat above all else.
There is also an in-universe reason that Grievous and Anakin never met each other. Anakin was instrumental in Darth Sidious' plan to overthrow the Republic and the Jedi. He needed Anakin for his machinations, but he also needed General Grievous to keeping razing the galaxy. He couldn't afford to lose either of them.
While the Jedi would remain his sworn enemy, Grievous was a threat to Force users outside their order as well. In fact, perhaps his greatest kill was not a Jedi at all, but a dark side adherent of such immense power that even Emperor Palpatine feared her as his equal.
Grievous Hero commanded the heroic Subjugator-class heavy cruiser Malevolence and followed Dooku's orders. Dooku later got fed up with Grievous's "failures" (due to plot armor) and tried to kill the heroic General by having a trap set up for him to "test his skills" in Grievous's castle.
Praven was a Sith pureblood male who served the reconstituted Sith Empire as a Sith Lord and later protected the Galactic Republic as a member of the Jedi Order.
In official canon, the Sith were an order of dark side Force users who used their abilities for personal gain. Canonically, the Sith who were not former Jedi include: Darth Sidious. Darth Plagueis.
Sidious wasn't scared of Grievous as he served him as a means to an end, rather that he was concerned about what the Kaleesh Cyborg would do if he ever knew about Sidious orchestrating both sides during The Clone Wars.
Legend had it that Yoda—a Jedi who became Grand Master—was trained by N'Kata Del Gormo. A Force-sensitive Hysalrian, N'Kata Del Gormo was trained in the ways of the Force and achieved the rank of Master within the Jedi Order.
The term “gray Jedi” in Star Wars is somewhat of a misnomer, considering that the definition refers to one who is practically non-Jedi. That being said, quite a few Jedi can be placed into this category. But Mace Windu identified as a Jedi despite his possible inclusion in the "gray" category.
Ok so let's get into it Mace Windu survives, The fall but he has lost his weapon and is servilely wounded in now hostile territory. This is why I believe he would go into hiding for some time thoughout the early years of The Galactic Empire.
Gray lightsabers are often associated with Jedi who do not fully follow the Jedi Code, but also do not fully embrace the Dark Side. These Jedi are often able to balance the light and dark sides of the Force and use their powers to serve the common good and are less likely to be influenced by the Dark Side.
