Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Tear Jerker: 07-Ghost
07-Ghost has Mikage's death. Teito surely isn't the only one who can't stop crying after that * sob*
Ayanami's backstory is sad, despite being the main villain. He fell in love with the chief of heaven's daughter, despite not having anything thing like feelings, and her soul was reincarnated in order to prevent it from falling Veloren's hand. So until he could find it, he attempted to take all the souls on the planet to find her. It is sad, but cruel.