Avantasia is a German supergroup metal opera project created by Tobias Sammet, vocalist of the band Edguy. It has been characterized as a rock opera, as it features the contributions of various vocalists and musicians and it consists of concept albums. The name is a blend of the words Avalon and fantasia ('fantasy') and describes "a world beyond human imagination" (a quotation from the booklet of the debut album).

Conceived in 1999 as studio-only, two-album project, Avantasia has since released seven other studio albums and has toured the world multiple times. It can be divided into four periods of activity. The first, 1999–2002, saw the release of a self-titled single and the full-length albums The Metal Opera and The Metal Opera Part II. The second, 2006–2011, consists of the EPs Lost in Space Part 1 & 2 and The Wicked Trilogy, composed of the albums The Scarecrow, The Wicked Symphony and Angel of Babylon. The third, 2013–2016, includes the albums The Mystery of Time and Ghostlights. The fourth period, 2019–2022, comprises the albums Moonglow and A Paranormal Evening with the Moonflower Society.

Some of the guest vocalists and musicians that have been featured on Avantasia are Michael Kiske, Jørn Lande, Alice Cooper, Klaus Meine, Dee Snider, Hansi Kürsch, Jon Oliva, Biff Byford, Joe Lynn Turner, Tim "Ripper" Owens, Geoff Tate, Kai Hansen, Rudolf Schenker, Bruce Kulick, Sascha Paeth, Eric Singer, Bob Catley, Roy Khan, Russell Allen, Timo Tolkki, Rob Rock, David DeFeis, Andre Matos, Sharon den Adel, Floor Jansen, Ralf Scheepers, Marko Hietala, Arjen Anthony Lucassen, Henjo Richter, Markus Grosskopf, Jens Johansson, Eric Martin, Ronnie Atkins, Oliver Hartmann, Mille Petrozza, Candice Night and Amanda Somerville.