Here are the many death of the Transformers from the movies, television show, and video games that I don't really enjoyed seeing.
10. Megatronus (Transformers: Robots In Disguise (2015)
The first Decepticon who was one of Thirteen Prime, guardian of entropy and transform into a Cybertronian tank. Seeing an all-powerful Prime getting defeat by three Autobots with enhancement by their Decepticon Hunter is very disappointed, I wish that he return.
9. Cliffjumper (Transformers: Prime)
An Autobot who was the partner of Jazz in FOC then later Arcee, a member of Team Prime, and transform into red Dodge Challenger with a horn ornament on the hood. He appear in a few episodes yet he get killed in the first episode by Starscream, now that bad idea even though it effect Arcee, plus he was voice by Dwayne Johnson which I bet make better of he was alive.
8. Sludge (Transformers: Power of the Primes)
An Autobot Dinobot who is the right leg of the Combiner Volcanicus and transform into a mechanical Apatosaurus. Oh come on Hasbro, do you really hate Sludge, first he was hurt and unplayable in FOC then you decide to let Rodimus Cron to kill him, now that was very unacceptable and no more Volcanicus.
7. Jetfire (Transformers: Revenge Of the Fallen)
A former Decepticon Seeker who change side to the Autobot, play a key role for defeating the Fallen, and transform into a Lockheed RC-71 Blackbird. A very funny old Transformers who decided to sacrifice himself to help Prime with a cool upgrade, at least it better than him getting killed like in the video games of the same name.
6. Metroplex (Transformers: Fall Of Cybertron)
An Autobot Titan who is the largest playable character in FOC, play a key role of Autobot's survival, and transform into a god damn city. Metroplex is an awesome character and killed Megatron, but it was sad that he sacrifice his himself to fuel the Ark.
5. Ironhide (Transformers: Dark Of The Moon)
An Autobot who is the weapon specialist, enjoy to kick some Decepticon asses, and transform into a black 2006 GMC TopKick C4500 medium-duty truck. A very badass characters in the three films and video games but they decided to let Sentinel Prime kill him with an acid gun, is worse than his G1 counterpart getting killed by Megatron point blank at the face.
4. Jazz (Transformers (2007)
A Autobot who is the lieutenant and second-in-command, enjoy the culture of Earth, and transform into a silver Pontiac Solstice Custom Hardtop GXP. A very cool Autobot with sunglasses or should I say visor, so why did they decided to kill off the third most lovable Autobot.
3. Rhinox (Beast Machines: Transformers)
A Maximal who is the second-in-command, a veteran of the Beast Wars, and transform into a rhinoceros then later become the Vehicon Tankor who turned into a Cybertronian tank. I like this character as he seem as he tried too use his beast mode new abilities but I was very sad to see him gone, at least he redeem himself for his actions.
2. Dinobot (Beast Wars: Transformers)
A former Predacon who follow a Samurai Bushido code, have a grudge with Rattrap, and transform first a Cybertronian excavator then a Velociraptor on Earth. He is one of my favorite BW character, it very sad that he sacrifice himself to save the humans of the future and terrible to make a clone of him, at least he got his memory back at the end.
1. Ratchet (Transformers: Age Of Extinction)
An Autobot who is the medical officer, help Bumblebee to try to fix his voice, and transform into a LA Fire Department search and rescue 2004 Hummer H2. I never expected they made AoE, but most surprise that many Transformers died which includes Ratchet getting his Spark rip from his body by Lockdown, another class died and now only two Autobots from the first film remain.
Secret 11. Optimus Prime (The Transformers: The Movie)
The death of the iconic leader in the 1986 film was a very horrible scene, killing many of the main characters only to replace them with new characters to sell new toys.
Here are some honorable (or should I say) mentions
Prowl (Transformers Animated)
Thunderwing (Transformers: Prime - The Game)
Zeta Prime (Transformers: War For Cybertron)
Canopy (Transformers: The Last Knight)