Superman's Kryptonite Question

What is Superman's "Kryptonite". In literature, mythology, and comic books heroes often have a "kryptonite" or "Achilles's heel", basically a weakness that makes them vulnerable. I'm curious what fans here would consider to be Superman's "Kryptonite"?

A screenshot of a Reddit post asking what Superman’s personal weakness might be, comparing kryptonite to an Achilles’ heel. The joke is an open-ended fan discussion about what could make an otherwise powerful superhero vulnerable. EN: A screenshot of a Reddit post asking what Superman’s personal weakness might be, comparing kryptonite to an Achilles’ heel. The joke is an open-ended fan discussion about what could make an otherwise powerful superhero vulnerable.

• @memetutorial / 19338 2025-04-10