Who is even stronger than Zeus?

Answer 1

There are many things that are stronger than Zeus.

Time might be one of them -- though he started his reign by usurping Cronos' throne - which would be a symbol of his power being mightier than that of time. In time, stories of gods on Mount Olympus were left just that: stories.

Man could be another. After all, Greek gods need men to build their altars and worship them. Greek gods weren't really creators of men (Prometheus the titan created people in Greek mythology), and showed no interest in them except they wanted to be served. As soon as men would realise they weren't really important, their strength would vanish.

Answer 2

In Greek mythology, Primordial deities such as Chaos, Chronos (Time), and Ananke (Necessity) are considered stronger than Zeus as they are the forces that predate the Olympian gods. Additionally, Titans like Cronus, father of Zeus, were also powerful beings who rivaled Zeus in strength but were eventually overthrown by him.