Here are most of the enemies/villains in Sonic:
1. Mephiles the Dark
2. Mammoth Mogul
3. Dr. Robotnik
4. Eggman Nega
5. Eggman Empire
6. Suppression Squad
7. Patch
8. Scourge
9. Dimitri the Echidna
10. Finitevus
11. Fiona Fox
12. Princess Alicia
13. Miles
14. Anti-Boomer
15. Rosy The Rascal
16. Black Doom
17. Snively
18. Lien-Da
19. Drago
20. Destructix
21. Lightning Lynx
22. Sergeant Simian
23. Predator Hawk
24. Flying Frog
25. fagiolo the Dynamite
26. Bark the Polarbear
27. Fang the Sniper
28. Scratch
29. Grounder
30. Coconuts
31. Chaos
32. Metal Sonic
33. Metal Scourge
34. Dark Gaia
35. Luna
36. Lavinia
37. Heavy
38. Bomb
39.Ixis Naugus
I hope te enjoyed reading. XD
1. Mephiles the Dark
2. Mammoth Mogul
3. Dr. Robotnik
4. Eggman Nega
5. Eggman Empire
6. Suppression Squad
7. Patch
8. Scourge
9. Dimitri the Echidna
10. Finitevus
11. Fiona Fox
12. Princess Alicia
13. Miles
14. Anti-Boomer
15. Rosy The Rascal
16. Black Doom
17. Snively
18. Lien-Da
19. Drago
20. Destructix
21. Lightning Lynx
22. Sergeant Simian
23. Predator Hawk
24. Flying Frog
25. fagiolo the Dynamite
26. Bark the Polarbear
27. Fang the Sniper
28. Scratch
29. Grounder
30. Coconuts
31. Chaos
32. Metal Sonic
33. Metal Scourge
34. Dark Gaia
35. Luna
36. Lavinia
37. Heavy
38. Bomb
39.Ixis Naugus
I hope te enjoyed reading. XD