A very underrated sad backstory is Man-Bat's. While most people know he accidently turned himself into a bat, Batman mistook his appearance for a mask and tried taking it off which horrified Kirk (he'd previously been helping Batman fight criminals). When he flew back to his lab to cure himself, Batman chased after him and kicked his only cure onto the ground. Kirk has since forever been trapped as a Man-Bat. His animal side (like Waylon Jones) has slowly overtaken his human rational side so now he no longer knows how to recreate the cure.
Imagine seeing your parents being crudely eaten by a titan in your f*cking face
Villain: Scarecrow (Two-Face's backstory isn't too great either)
bruce wayne
bruce benner
punisher
Emiya Kiritsugu
Sakura Matou
Furude Rika
Ren Fuji
Hajun
Batman
Emilia
Tyrion Lannister
Arthur Morgan
Liquid Snake
Guts( Berserk)
Ray,Norman,and Emma ( The promised Neverland)
Edward Elric(Fmab)
Itachi uchiha(Naruto)
Future Trunks (Dragon ball)
Batman
Rorschach
Magneto
Loki
Kurapika kurta (HunterxHunter)
Chrollo lucilfer(HxH)