Captain America's most formidable opponent that he has defeated is Cosmic Red Skull, an entity who had attained the power of a cosmic god.
The Cosmic Red Skull Challenge
The Red Skull, Captain America's long-standing nemesis, managed to acquire cosmic power not once, but twice. Each instance saw him wielding immense, god-like abilities, posing an existential threat. Despite the vast power disparity, Captain America, armed with his iconic shield and an exceptionally potent photonic sword, managed to overcome this cosmic entity.
This victory underscores Captain America's unparalleled resolve and strategic prowess, allowing him to defeat a foe who had transcended mortal limitations and achieved divine power. His consistent ability to defeat such a powerful adversary, even when powered by cosmic forces, highlights his status as one of Earth's most resilient heroes.
