Tear Jerker / Transformers: Shattered Glass

• While we're never shown exactly what happened to the mirror-universe version or Rumble, who was about to be executed in the smelting pools. Though Cliffjumper tried to save him, his ultimate fate was likely, not a happy one.
• Sideswipe's backstory, while he was once a loyal Autobot minion. The evil Optimus eventually betrayed him and set him up during an ambush to be killed. Though it's not so bad, since the Decepticons willingly took him in afterwards.
• Megatrons' death. What makes it worse is that it didn't mirror any one of Optimus Prime's deaths. He didn't even have a choice in the matter, he was murdered by one of his own men.
  • Despite the Narm, Starscream's reaction was palpable.
• Also, Nightmare Fuel, at the end of "Invasion". Ultra Magnus manages to destroy an entire universe. Not only are the Heroic Autobot's and Deception's appalled by the scope of Magnus' plan. Even the normal-verse Decepticon's are disgusted and horrified by what the evil Autobot and his men had just done.