The Colossal Titan was one of the Nine Titans and served as the primary antagonist of the first three seasons of Attack on Titan series. It was notable for its incredible size and its ability to control both the steam emitted by its Titan body and the amount of energy released during its transformations.
Abilities: Although all Titans generated enormous amounts of heat and energy during transformation, the users of the Colossal Titan could control the energy they produced to create various effects. For instance, when Bertholdt Hoover attacked Trost District his transformation only causes a wind blast that knocked some cadets over the Wall. However, during the battle of Shiganshina District, Bertholdt released a much larger explosion, creating a mushroom cloud of dust and rubble, ravaging part of the city, and instantly killing a great number of Scout Regiment soldiers.
History: The Colossal Titan, like all the Nine Titans, was brought into the world after the death of Ymir Fritz. In the 1,800 years following her death, the Colossal Titan was held in the possession of one or several of the warring Eldian houses subservient to the Founding Titan. After these seventeen centuries when Karl Fritz, the 145th King of the Fritz family, abandoned the conflicts of Eldia and relocated to Paradis Island, the Colossal Titan was taken by the nation of Marley during the Great Titan War.
Story: The Colossal Titan makes its first appearance outside Wall Maria when Bertholdt transformed outside the southern gate, terrorizing the population of Shiganshina and kicking a hole in the southern gate. Its actions allow the Pure Titans wandering outside to enter Shiganshina, where they begin to feast on its many inhabitants, including Carla Jaeger. Bertholdt joined his fellow surviving Warriors in entering the walled territory during the chaos.
Trivia: In the game Age of Gunslingers Online, a special Titan Mode was made as a tribute to the series. The final boss is heavily based upon the Colossal Titan and is fought atop a massive structure. v=VsI7vY6dA2k here].
Source: Colossal Titan (Anime), available under CC BY-SA 3.0.