Its body in its 50% Forme is shaped like the letter "Z" and appears to be a snake. It has a green top half and a black bottom with 5 Pillar-like shapes on its back. It has no arms or legs and has a various amount of scales on its body. Zygarde has two compound eyes and green shapes under them. It has a tail which is flat.
Zygarde Complete Forme has a large, humanoid body with a long tail similar to Zygarde 50% Forme's body. The very tip of the tail can open up, making them appear to be a mouth. There are several flat protrusions around its head and triangular protrusions around its neck, giving it a crown-shaped appearance. On its face are three white hexagonal marks: one in the middle of its forehead with a line through it and two being that acting as eyes. There are an additional five green hexagons on its face: four along the bottom and one in the middle of a short protrusion on top. Each shoulder has two wings protruding from it. These wings all have a hexagon and an undulating pattern: blue on the right side and red on the left. The very tip of the wings can open up, making them appear to be a pair of "mouths" with red or blue patterns on the inside. It has multiple white protrusions on its body: three on each hand acting as claws, one on each knee, and one and the front of each foot. Additionally, there are green extensions surrounding its wrists and two under the white protrusions on its knees and feet. Its abdomen has a vertical, hexagonal pattern upon it with two thin, white, and vertical marks on either side. Across its chest is thin, zigzagging opening that fades between five colors: red, orange, white, cyan, and blue. The chest can open, revealing five cores of each color. Above this opening are two large green, hexagonal marks. When its wings and tail are extended, Zygarde Complete Forme resembles the Latin alphabet letter Z.
Zygarde 10% Forme has a relatively small, mostly black Dog-like body with a green "scarf" that continues beyond the neck. Its muzzle is black at the top and green elsewhere. Its eyes are white hexagons with a black outline and no discernable pupils; directly above the eyes are two small green hexagons which resemble eyebrows. On its forehead is a very thin, white ellipse. Its "scarf" is entirely green with a small hexagon connected to the bottom. This hexagon is either red or blue depending on which Core it is comprised of. On each of its legs are hexagonal protrusions, all the same color black as the legs themselves. On the front two legs, there are two. On the back legs are three protrusions, and on the left leg is a particularly long one made up of two hexagons. On each of its hind legs is another hexagonal shape, with a noticeable gap before a small square protrusion above it.
Zygarde Core is a part of the mind of Zygarde, and has a small and leafy-green gelatinous body comprised of a large, round head, a moderately-sized body, and a thin, hook-shaped bottom section which may be a tail. Its head is rounded except for a protruding, beak-shaped area at the bottom front which may be a nose or a mouth. Within its head is a single, oval eye which has a smaller black, oval pupil within it. Beside this eye is another white, semi-elliptic shape which may be a second eye. Within its midsection is a nearly regular hexagon. There are two known Zygarde Cores, one composed of a red hexagon and one composed of a blue hexagon. They are self-aware and can communicate via telepathy, monitoring the ecosystem around them. Zygarde Cores get their energy through photosynthesis.
Zygarde Cells make up Zygarde, and appears very similar to the Zygarde Core. Unlike the Core, it is flat, has a green pupil, and has a darker green, more elongated hexagon within its midsection. Unlike the Cores' hook-like bottom section, the Cells have a long and more noticeably tail-like back-end. The Cells lack minds of their own and are incapable of independent thought, and are entirely controlled by the Cores, which use them as "appendages" and "surveillance cameras" to keep an eye out of their surroundings.
Zygarde is part of a legendary trio that include Xerneas and Yveltal, together spelling X, Y and Z, the last letters of the alphabet. They also happen to be the last Pokémon in the Mountain Kalos Pokédex.
Zygarde is the only Legendary Pokémon to have more than four formes (excluding Arceus and its type changes).
Zygarde 50% Form is based off of a serpent in the form of the letter Z. It may also be based on Nidhogg, the serpent that lives on the roots of Yggdrasil.
Zygarde 10% Form is based off of a Doberman Pinscher on a green leash, or perhaps the great wolf Fernrir.
Zygarde Cell and Zygarde Core are based off of cells and possibly planaria. They also may be based on neurons.
Zygarde Complete Form is based on Hel, a Nordic goddess. It also incorporates some features of mecha robots in anime.
Zygarde's name has been derived from two words. "Z(ee)" responds to Z axis and "garde" is a French word meaning guard or protection. It may also be based on zygotos meaning "divided". It is a part of Yggdrasil Trio.
Red Zygarde Core
Red Zygarde 10% Forme
Zygarde 50% Forme
Zygarde Complete Forme
Zygarde's 50% Forme as shown in the Pokémon Dream World