From zombie apocalypses to cosmic plagues, fictional infections have terrified and fascinated audiences across every medium. This ranking explores the most unhinged, reality-warping diseases and parasites ever conceived—from the fungal horrors of *The Last of Us* to Warhammer 40K's Chaos-spawned nightmares, the rage virus of *28 Days Later* to *Resident Evil's* T-Virus catastrophes.
Spanning video games, comics, anime, and film, these entries showcase infections that turn humans into monsters (*Left 4 Dead*, *Dying light*), cosmic parasites that consume galaxies (*Metroid*, *Destiny*), and reality-bending plagues that defy comprehension (*DOOM*, *Crossed*). Whether it's the Radiance's mind control in *Hollow Knight* or the Kaiju-spawning parasites of *Pacific Rim*, each infection brings its own brand of existential dread. Discover which fictional pandemic reigns supreme in sheer insanity and destructive potential.