Trans-Siberian Orchestra (TSO) is a progressive rock band founded as an outlet for the many rock operas late rock industry veteran, producer, composer, and musician Paul O'Neill was writing.

TSO was created to push the boundaries of what was possible for a band to create - both musically and visually. Paul O'Neill dreamed of a different kind of "band" that is not limited by the confines of traditional rock acts and instead established one with multiple singers who could inhabit the various characters he was writing into his rock operas.

Although TSO is best known for their Capra-esque trilogy of holiday records - Christmas Eve & Other Stories, The Christmas Attic, and The Lost Christmas Eve - they have also released several other rock operas. Beethoven's Last Night (2000) was the first of these non-holiday rock operas and tells a compelling tale of a battle for Beethoven's soul between good and evil. It features instrumental crossovers between classical composers and contemporary rock, along with original vocal tracks featuring Patti Russo (Meatloaf) as the character Teresa, Beethoven's love. Later albums take on great themes such as war and redemption, namely Night Castle (2009). Night Castle was TSO's first Top 5 album debut and included a bonus track featuring Greg Lake (Emerson, Lake & Palmer, King Crimson), who was one of TSO's greatest influences. Letters From The Labyrinth (2015) was another Top 10 release for TSO. In total, TSO has sold in excess of 12 million albums and DVDs.

Consistently one of the Top 25 touring acts in the country, TSO shows no signs of slowing down. Since its touring debut in 1999, TSO has played over 2,000 Winter Tour shows for more than 18 million fans. So far TSO has also donated over $18 million dollars from these tours to local charities.

At the time of his passing, O'Neill had several TSO projects in various stages of completion at his recording studio in Florida. He also had two finalized rock operas: Romanov: When Kings Must Whisper, about the 1917 Russian Revolution, along with a live concert adaptation of Night Castle. O'Neill also planned to eventually bring the TSO experience to Broadway. Nearly 25 years after the release of their first album, Trans-Siberian Orchestra continues to create and live on.