Metteyya (Pali) or Maitreya (Sanskrit) means ‘The Loving One’ or ‘The Friendly One’ and is the name that the Buddha of the next era will be known by (D.III,76).
At present, Metteyya is a bodhisatta abiding in the Tusita heaven, practicing the spiritual qualities that will lead to his enlightenment in the distant future. In most Buddhist iconography Metteyya is depicted as a beautiful young prince with a stupa in his crown. In late Chinese art he is often depicted as a rotund smiling figure, so as to emphasize his approachability and his warm friendly nature, and is inelegantly and incorrectly dubbed ‘Laughing Buddha’ by some Westerners.
The Mahayana and some of the Theravada commentaries places the arrival of Metteya at approximately 5,000 years after the passing of Buddha, which would make it somewhere around the year 4517 which is about 2,500 years from now. The early Theravada discourses hold that there is no set date and that it depends upon when the Dhamma disappears from the world and when the conditions are right, which could be that far off or even longer.
See also: 28 Buddhas