* Kryptonite: This radioactive mineral from Superman's home planet Krypton is his most famous weakness. Exposure to kryptonite weakens Superman, making him sick and susceptible to injury. Different types of kryptonite have different effects, some being more deadly than others.
* Magic: While Superman is incredibly strong, he has shown vulnerability to magic. Characters with magical abilities have been able to hurt Superman, even when he is otherwise invincible.
* Red Sun Radiation: Superman's powers are fueled by the yellow sun of Earth. Exposure to red sun radiation, like that of his home planet Krypton, weakens him and eventually drains his powers completely.
* Certain Psychologically-Based Attacks: While Superman is incredibly resilient, he can be vulnerable to psychological attacks. Some villains have been able to exploit his human emotions and sense of morality, making him question his actions and momentarily weaken him.
It's important to remember that Superman's vulnerabilities have been explored and portrayed differently over the years, depending on the writer and the story being told.