Over the course of a career now spanning a quarter century, Dream Theater have arguably become the prototypical progressive metal band. And, not by coincidence, they are also probably the most successful purveyors of the form. Dream Theater was founded in Boston, Massachusetts, in 1985, initially as Majesty, by fellow Berklee College of Music students John Petrucci (guitar), John Myung (bass) and Mike Portnoy (drums). Together with keyboardist Kevin Moore and vocalist Charlie Dominici, the quintet recorded 1989’s When Dream and Day Unite for independent Mechanic Records — then parted ways with both the label and Dominici prior to releasing their breakthrough sophomore album, 1992’s Images and Words, introducing new singer James LaBrie. The song “Pull Me Under,” in particular, became a surprise hit for Dream Theater (still the biggest of their career), despite exceeding the eight-minute mark, and gave the band the confidence to pursue their ambitious musical template, marked by fantastic virtuosity and diversity, over a string of ‘90s albums while developing a rabid following on tour. For 1999’s conceptual Metropolis Pt. 2: Scenes from a Memory, Dream Theater welcomed keyboardist Jordan Rudess (replacing Derek Sherinian, who, in turn had replaced Moore in ’94), and this lineup would enjoy continued stability and success into the new millennium, thanks to acclaimed offerings like 2003’s Train of Thought and 2007’s Systematic Chaos. Not until 2010 would their winning streak be challenged by the not-quite-friendly departure of founding member and longtime band leader Mike Portnoy. But Dream Theater’s remaining lineup ultimately prevailed and still prospers today with help from new drummer Mike Mangini — their progressive metal supremacy still relatively unchallenged.