General Grievous

General Grievous is the supreme cyborg commander of the CIS Droid Army and a major antagonist in the Star Wars universe. He first appeared as a minor antagonist in Season 2 of the Legends 2003 miniseries Star Wars: Clone Wars, and later served as the main antagonist of Season 3. He is also the secondary antagonist of both Star Wars: Episode III - Revenge of the Sith and the 2008 TV series Star Wars: The Clone Wars, and a posthumous antagonist in the 2019 video game Star Wars Jedi: Fallen Order.

Why He Rocks
1. He is a very intimidating threat in the Legends continuity and the 2003 series

2. He's also a complete badass, he fought 5 jedi and kills one of them. Making him really terrifying.

3. His backstory is a bit heartbreaking, where he lost his love interest and his people suffering from starvation.

4. His hatred against the jedi is pretty understandable, his killings of the jedi are justified.

5. His voice in the 2003 series sounds really threatening then how he sounds like today.

6. He is basically a foreshadowing of Darth Vader.

7. His fighting skills are awsome in the 2003 series.

8. His design is pretty nightmare fuel, and awsome at the same time.

9. His character development is pretty good in legends, unlike how he was portrayed in Revenge of the sith and 2008 series.

10. Iconic theme song.

11. "Run jedi, run. You have only prolonged the inevitable."

12. "Jedi scum".

13. He took inspiration from Darth Vader.

14. Getting his cough from mace windu is a good explanation in the 2003 series. (Sadly it's no longer canon)

15. He becomes an internet meme.

16. In the 2003 series, he is pretty silent throughout the episodes.

Bad Qualities
1. Sadly, he was butchered in Revenge of the sith and the 2008 Clone wars series.

2. He was very weak, and gets beaten easily, even though he was supposed to be unstoppable.

3. He was treated like a joke in star wars: the clone wars.

4. He talks too much.

5. He gets beaten by gungans, I'm not even kidding! He gets beaten by the annoying gungans. When he should've have killed them in a second.

Trivia

 * In his first appearance in the Legends miniseries Star Wars: Clone Wars he was significantly more powerful than in his later appearances, being able to defeat multiple members of the Jedi council at once with relative ease.