Missing Member: Frontman Dennis DeYoung, 1999 to present.
Background: Styx reformed for a series of reunion tours with Dennis DeYoung in 1991, 1996 and 1997, but old tensions between the singer and guitarist Tommy Shaw resurfaced very quickly. "We're just different people with different desires and different vision of how things should be," Shaw told Rolling Stone in 2011. "God, it was such an unhappy place. Insanity is doing the same thing over and over and expecting a different result." After the 1997 tour, DeYoung began experiencing an extreme sensitivity to light that made touring impossible. The group eventually grew tired of the situation and began touring with replacement Lawrence Gowan.
Impact on Reunion: Minimal. Styx are one of those bands where the songs are more famous than the musicians. A good many people know every word to "Come Sail Away," but couldn't pick Dennis DeYoung or Tommy Shaw out of a police lineup. That has helped them tremendously in the post-DeYoung era. They go out and play sheds every single summer on double bills with the likes of Foreigner and REO Speedwagon and earn a very good living. DeYoung, meanwhile, plays much smaller venues with a guitarist that used to play Tommy Shaw in a Styx tribute act.
Odds of a True Reunion: DeYoung has made it clear he'd reunite with them at any point, but the others have absolutely no interest. They'd rather make slightly less money and not deal with him than try yet another reunion. But then again, the history of rock reunions has showed us that nothing is impossible so long as people are alive and physically able to perform.