Parasyte

is a manga series written and illustrated by Hitoshi Iwaaki, and published in Kodansha's Afternoon magazine from 1988 to 1995. The manga was published in North America by first Tokyopop, then Del Rey, and finally Kodansha Comics USA. The manga has been adapted into two live-action films in Japan in 2014 and 2015. An anime television series adaptation by Madhouse, titled, aired in Japan between October 2014 and March 2015.

Plot
They arrive in silence and darkness. They descend from the skies. They have a hunger for human flesh. They are everywhere. They are parasites, alien creatures who must invade - and take control of - a human host to survive. And once they have infected their victims, they can assume any deadly form they choose: monsters with giant teeth, winged demons, creatures with blades for hands. But most have chosen to conceal their lethal purpose behind ordinary human faces. So no one knows their secret - except an ordinary high school student. Shin is battling for control of his own body against an alien parasite, but can he find a way to warn humanity of the horrors to come?

Official

 * Parasyte Anime Website (Japanese)
 * Parasyte Manga Website (Japanese)
 * Parasyte Manga Website (English)

Other Sources

 * Parasyte on Wikipedia
 * Parasyte manga on AnimeNewsNetwork
 * Parasyte anime on AnimeNewsNetwork
 * Parasyte live action on AnimeNewsNetwork