Gyarados is water type pokemon that was originally introduced in Pokemon Red and Blue. It evolves from Magikarp starting at level 20. As the pokemon games have developed Gyarados has become one of the fan-favorite pokemon in the pokemon game series. It's shiny form (below) is nearly identical except for instead of being primarily a light blue it is a red color instead.
Another form of Gyarados is zombie Gyarados (charred Gyarados). Zombie Gyarados can be made by catching a Magikarp while it is on fire and then evolving the Magikarp into Gyarados. Gyarados spawns in Ocean and Deep Ocean biomes, and occasionally is possible to be found in Beach biomes.