John Nicholas "Jon" Oliva (born July 22, 1959) is an American singer and musician. He is best known as the co-founder, keyboardist and lead vocalist of the heavy metal band Savatage, which he co-founded with his younger brother Criss Oliva. Since 1996 he has also been a songwriter, musician and vocalist in Trans-Siberian Orchestra. Producer Paul O'Neill referred to Oliva in numerous interviews as the single greatest vocalist/musician he has ever worked with.
Description above from the Wikipedia article Jon Oliva licensed under CC-BY-SA, full list of contributors on Wikipedia.