Most notable among these was heavy metal band Vengeance in the 1980s, and in the '90s, the progressively experimental Ayreon, whose every album featured guest vocalists like Kingdom Come's Lenny Wolfe, Marillion's Fish, and the Gathering's Anneke van Giersbergen -- usually enacting different characters in virtual art rock operas. Somewhere in between lay his new millennium project Arjen Anthony Lucassen's Star One, whose grandiose ambitions were pretty much described by 2002's Space Metal and its live companion piece of a year later, Live on Earth. Both also featured a revolving cast of guest performers, including Rising Force and Stratovarious alum Jens Johansson, Edge of Sanity singer/guitarist Dan Swano, and Shadow Gallery guitarist Gary Wehrkamp. Another project, Stream of Passion, featured Lucassen with Mexican singer Marcela Bovio; that band released several albums during the 2000s and 2010s. ~ Eduardo Rivadavia