Gotou is an experimental Parasite created by Reiko. He is actually composed of several combined Parasites, whose shapeshifting ability has advanced to the point where they can switch positions, each forming a different limb as the situation requires.

He is the most intelligent and skilled, and is the de facto leader of the composite body. Because his head and all of his limbs are made of Parasite cells, Gotō is much faster, stronger, and more dangerous than standard Parasites, and nearly impossible to injure. The name "Gotou" is a pun on a word "五 Go" meaning number 5, implying he can control 5 Parasites, whereas the other Parasyte in the same body called Miki (三木 Miki lit. three trees) can control only 3.

(Source: Wikipedia)