A TF's soul/persona is in their spark. The Spark chamber is in the chest. TFs can lose limbs with little impact (arms, legs). TFs can function despite massive head wounds (Megs, aka "Massive Headwound Harry"). In some TF universes, like Animated, moving the spark to a new body moves the TF's persona/soul. So given all this: Are decapitated TFs actually dead? Or are they instead massively disabled and offline, their sparks in emergency stasis? Perhaps they need a steady, low level supply of Energon to remain in said stasis, but nonetheless. It makes some solid sense that head damage or even removal does not kill their spark. This would mean that as of the end of DOTM: Sentinel Megatron Shockwave (maybe, he also took some heavy chest damage) Starscream Bonecrusher (from movie 1) and *maybe* Soundwave (depends on whether BB's blast up the car hood/chest took out the spark chamber or not) Grindor Devastator are all still alive, but disabled and in stasis. You can imagine a scene where NEST and the Autobots secure their lined up, in-stasis bodies in a super secure storage room on low-level energon feeds. Maybe that scene, with Prime explaining it, starts movie 4? Sadly, Ironhide and Q are pretty certainly dead - especially Ironhide as Sentinel went for the kill shot to the chest (which makes sense if you're trying to destroy the spark, right?). Also, it's safe to assume Brawl, Blackout, and countless other "shot to pieces" Think about it. Megs died in movie 1 because his spark was destroyed (chest). Prime was killed in ROTF when Megs very deliberately went for the chest shot (spark-kill). The Fallen and Jetfire - killed when their spark chambers where removed and destroyed. Brawl and Blackout only went down in movie 1 after enough damage to their chests. If decapitation doesn't kill, it changes Prime's obsession with faces/heads significantly, no? Prime goes for the massive disabling but not spark-kill-shot? Other than the Fallen, Prime never goes for the spark/chest. Only heads. Megs and Sentinel went for the spark chambers for kills every time. (Assuming Jazz died from chest-area damage when torn in half). Just a theory that I found interesting when I thought it out. Corollary 1: Of course, having a secure room full of the most dangerous Decepticons (and Sentinel) in stasis means the destruction of Earth and the Autobots is only ever one Decepticon infiltration or human/bot betrayal away. That's not a fun idea for the Autobots or humans. I wonder if the humans would allow it, actually? Corollary 2: If decapitation doesn't kill Decepticons then we have 3 war movies with very few casualties. Reminds me of a 1980's cartoon, no? Corollary 3: And if decapitation *does* kill TFs, then all three Bayverse movies still have a lower kill count than the '86 movie.