What's a band that you like that was gone way too soon?
For example, a band like Joy Division. Two masterpiece albums in the form of Unknown Pleasures and Closer, and the untimely death of Ian Curtis cut it all short. They were even heading into the direction that New Order eventually went in, and it would have been interesting to see what Ian Curtis would have done if they fully made the leap into electronic music while he was still alive.
Foreground Eclipse, easily the best screamo (maybe?? i dont know music words) band I've ever listened to. Bands like katikatiyama and Shinigiwa Satellite (some members of which became the aforementioned KKY) fill that void, I'll never get over the sheer mastery of mixing screaming and clean vocals.