-Unicron. A planetoid was blown up INSIDE OF HIM, and he gave no shits whatso-blam!-ingever. -Most of the Thirteen Primes. One of those guys sat down on the surface of a star to meditate, and another took hours/days to die after being suckerpunched with a planet busting weapon. -Stealth Bomber Megatron, probably. He flew through an asteroid several miles wide with no damaged whatsoever, survived attacks that were ripping apart a planet, and then survived being essentially reduced to a skeleton. I'm the least sure of this one, but I could see him pulling it off. -IDW Galvatron. -blam!-er's just crazy. His own gun can potentially blow planets up. He survived an alternate universe literally designed to kill all living things, which Cybertronians technically are.... This one, like SB Megatron, is arguable, but I certainly wouldn't be surprised to see Galvy pulling it off. -Heisei Godzilla. His cells apparently survived passing through a black hole. This asshole is so bullshit tier. Doesn't matter if you put him down. He'll eventually heal and be back. Never actually dies. Hell, you can accidentally make more if you separate bits of him and expose them to significant radiation. He's like a terrifying, sentient starfish lizard with a bad attitude.