* The LittlestCancerPatient Shirley in the second season. Made worse by her friendship with Bart and his going into an UnstoppableRage to save an her on a planet from the Harvesters only to find out she died during the battle from her disease. A double whammy comes from the show cutting to her trying to hold on so she can see Bart again.
* The RedShirtArmy at the end of the first season. Hibiki meets them, they get some depth and they aren't going let their planet get harvested, and the harvest fleet they were trying to stop proceeds to effortlessly tear them apart while Hibiki is powerless to help them.