I used to have an adorable Orange tabby, she died of some unknown condition in my arms :(
I also own two snakes that need feeding once every other week, so I let my rats make babies so I can feed the babies to the snakes >_>.... it's extremely cost effect but heartbreaking :C
Also, my Pet rat (NOT A FEEDER RAT) is named Rattata <3
That's, uh... disturbing...
The only pets I've had die are a few fish, but I was visiting my friend once and his dog ate his brand new kitten right in front of our eyes... It was horrible...