I can't believe I haven't done this yet, I'm a huge fan of this Mythos, in fact it has probably been my most favorited and influential mythology ever, only second to perhaps the Lovecraft Mythos. Again, my list may change from time to time, but so far these are my top favorite Gods, Titans, Monsters, Heroes, Villains, Demigods, and many more within Greek Mythology.
Feel free to please have your own list, and again, it doesn't even have to be 20, I just have a lot so it is REALLY hard to choose sometimes. And I know versions of Greek Mythology vary so please just favor which ever one you want, although it'd be cool for people to actually give somewhat of legitimate instead of the you know..."Because of God of War" Excuse.
Anyways, lets get started.
20. Hephaestus-God of the Forge
19. Atlas-The Titan of Strength
18. Persephone-Goddess of the Underworld
17. The Minotaur-The Beast of the Labyrinth
16. Cetus-The Sea Serpent
15. Athena-The Goddess of Wisdom
14. Medusa-The Gorgon Queen
13. Echidna-The Mother of Monsters
12. Morpheus-The God of Dreams
11. Thanatos-The God of Death
10. Gaia-The Primordial Mother Earth
9. Chronos-The Primordial God of Time
8. Erebus-The Primordial God of Darkness
7. Hades-The God of the Underworld
6. Eris-The Goddess of Discord
5. Hydra-The Multi-Headed Serpent
4. Typhon-The King of Monsters
3. Nyx-The Primordial Goddess of Night
2. Prometheus-The Titan of Forethought
1. Chaos-The Void
Hope to see your top few too.