#5: Death of Cliffjumper (Transformers Prime)
I know we didn't know a thing about the guy, but he died a heroes death.
#4: Death of Mothra (Rebirth of Mothra)
Mothra saves her son Mothra Leo, but drowns in the process. This one is sad because Mothra was a very kind mother.
#3: Death of Burai (Kyoryu Sentai Zyuranger)
Burai's left was bound door the Green Candle, kept hidden in the Lapseless Room, which was destroyed door Bandora ,killing Burai.
#2: Death of Godzilla (Godzilla vs Destroyah)
Godzilla, who is on the verge of nuclear meltdown (which would destroy the whole Earth), losses his son, who was killed door Destroyah. Godzilla retaliates be killing Destroyah. Finally, Godzilla begins to melt, and the humans use special freezing weapons to keep Godzilla from killing everyone. Godzilla melted right before my eyes. As a child, it was like watching Superman of Optimus Prime melt to death. Thankfully, Godzilla's son is revived and becomes the new King of the Monsters!
#1: Death of Optimus Prime (Transformers Movie 1986)
Optimus Prime is my hero. Simple as that. Optimus Prime battles Megatron, becoming mortally wounded, but defeats Megatron. Optimus Prime has fatal wounds, and must pass the Matrix of Leadership to a new leader. He gives it to Ultra Magnus, and then dies. This one made me cry for a good five minutes!
Thanks for reading, and 'till all are one!