John Nicholas "Jon" Oliva 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.

Trans-Siberian Orchestra (TSO) is an American rock band founded in 1996 by producer, composer, and lyricist Paul O'Neill, who brought together Jon Oliva and Al Pitrelli and keyboardist and co-producer Robert Kinkel to form the core of the creative team. The band gained in popularity when they began touring in 1999 after completing their second album, The Christmas Attic, the year previous. In 2007, The Washington Post referred to them as "an arena-rock juggernaut" and described their music as "Pink Floyd meets Yes and the Who at Radio City Music Hall." TSO has sold more than 10 million concert tickets and over 10 million albums. The band has released a series of rock operas: Christmas Eve and Other Stories, The Christmas Attic, Beethoven's Last Night, The Lost Christmas Eve, their two-disc Night Castle and Letters From the Labyrinth. Trans-Siberian Orchestra is also known for their extensive charity work and elaborate concerts, which include a string section, a light show, lasers, moving trusses, video screens, and effects synchronized to music.