Red Skull, whose real name is Johann Shmidt, is Captain America's oldest and most infamous enemy. Rising from a troubled childhood in Germany, he became a ruthless agent of the Nazi regime before eventually leading HYDRA in his quest for global domination. Enhanced through experimental science and armed with a brilliant strategic mind, Red Skull has repeatedly challenged Captain America and the Avengers. His fanaticism, manipulation, and relentless pursuit of power have made him one of Marvel's most enduring villains.