Marvel: Self-Sustenance

Cain Marko (Juggernaut)
Juggernaut is completely self-sustained, he has no need to breathe, eat, or drink at all. He cannot tire, hence he cannot sleep. However, his self-generating mystical energies provide him with the nourishment of sleep, nutrition, hydration, and oxygen. He is sustained by his mystical energies alone. He once even kept talking and fighting after being reduced to a skeleton.

Kuan-Yin Xorn (Xorn)
Given the nature of his mutant abilities, Xorn did not need to breathe, nor did he require food or water to survive.

Shen Xorn (Xorn)
Given the nature of his mutant abilities, Xorn did not need to breathe, nor did he require food or water to survive.