The name Avantasia is a mixture of the words Avalon and fantasia (fantasy). It describes "a world beyond human imagination" (quote from the booklet).
Michael Kiske did not want to be named in the booklet, so he was credited as "Ernie" on the first CD. After the fans recognized him nonetheless, his real name was listed on Part II.
Tobias had actually wanted Tarja Turunen, former Nightwish vocalist, to sing the role of Anna on his Metal Operas but she declined. Sharon den Adel (from Within Temptation) took the role instead.