What is the most powerful greek monster?

Well that's easy, the Hydra! And the African Griffin is 1 of the 3 most powerful Greek monsters.

The three most powerful Greek monsters are the following:

1) The Hydra

2)The African Griffin

3)The Chimera

(the African griffin is only the of a fox, and can lift an adult African elephant)

The most powerful Greek monster was Typhon. Took down Zeus.