What can kill Hellboy?

Hellboy, a demon with superhuman abilities, can be harmed by various supernatural entities and artifacts. His vulnerabilities include being injured by mystical weapons or beings that possess divine or demonic powers, such as angels or certain magical beings. Additionally, his mortality can be compromised by specific spells or curses that target his demonic nature. Ultimately, while he is incredibly resilient, threats from powerful supernatural forces can potentially kill him.