Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Tear Jerker: XCOM: Enemy Unknown
By the time a soldier reaches the rank of sergeant and earn their own nickname, you will mostly have developed some level of attachment towards him/her after watching the raw recruit developed into a true badass hero. Therefore it makes it absolutely heartbreaking to watch them killed in battle, especially if it is the result of poor decision, since you are fully aware of the fact that YOU are partly responsible for the death.
It is worst if you are the type of role-player that imagine backstories and personalities for your soldiers.