* Ισχυρός σαν ταύρος (Ischyrós san taúros): This is a literal translation, meaning "strong like a bull." It's grammatically correct but might sound a bit stiff or unnatural to a native speaker.
* Δυνατός σαν βουνό (Dynatós san voúno): This translates to "strong like a mountain," which is a more common and naturally sounding idiom conveying immense strength.
* Ατσάλινος (Atsalinos): This means "made of steel" or "steely," implying great strength and resilience.
* Ακαταμάχητος (Akatamachitos): This means "unconquerable" or "irresistible," suggesting strength that cannot be overcome.
The best choice depends on the context. If you want a literal translation, use the first option. If you want something more idiomatic and impactful, the second, third, or fourth options might be better.