I thought of one: Savatage's Handful of Rain.
The band was struck by tragedy: Criss Oliva had died the year before. The band as we knew it was basically over, everyone was too grief stricken to consider at the time diving into another album, and so Jon Oliva basically wrote and recorded the album itself. He did EVERYTHING, he wrote it, he played drums, he did everything except the solos, given to Alex Skolnick, and obviously Zac Stevens sang.
So, we have a band emotionally disbanded after the tragic loss of a great songwriter, and a brother in grief writing an album all by himself. Shoud have been a forgivable trainwreck, right? .....hell no. Handful of Rain is a fantastic album and is completey on par with all the other ones. It's not the most famous but there are some seriously great tracks there, included the epic masterpiece Chance.
To even make a good album in those conditions was already something extraordinary. For the album to have one classic track that went on to become one of the most famous songs from the band is basically unreal and shows the greatness of Jon Oliva.
Morbid thought given the wake of Van Halen's passing: I hope he takes cares of his health for many, many years to come, after Criss and Paul O' Neill, we need to live in a world when there's at least an Oliva brother.