The conversations have always gone in this direction on unrelated posts, so let's debate this here: The status debate of villains.
Villains never die in shows, movies, or games, right? They "always survive". Well, not really, but fans are just unable to accept it unless it's someone they really want dead like Joffrey or Ramsay from Game of Thrones. (So where's all the "I think the fan favorite hero survived?" People said Blaze's death carried over to the revised timeline until she turned up in Generations)
It is true Eggman always survives when we think he gets blown up, but he's Eggman, he has to stay in the series for as long as it goes on. If Sonic Mania is last, and he seemingly gets blown up again, there'll be more debate, but it's to be expected. The others on this list, with two exceptions, are one-shot.
So, let's review all the major villains to ever die in the series - or not.
Egg Robo and Mecha Sonic
The main villains of Knuckles's storyline in Sonic & Knuckles. Egg Robo takes Knuckles to Mecha Sonic for death, Mecha Sonic aims a Spin Dash at Knuckles, but Knuckles dodges and Mecha Sonic smashes into Egg Robo, who explodes into pieces like any other boss in the game other than Eggman himself. Then Knuckles fights him with the best soundtrack in the game, and in the end he explodes into pieces the same way. He does appear in the end credits scene, but that'll be non-canon, there's no way he recovers from that, and Eggman built a replacement for him, Metal Sonic.
Grand Battle Kukku 15th
The main villain of Tails Adventure. Tails fights him with bombs, and eventually he explodes, gone.
Black Doom
The dark and sinister main villain of Shadow the Hedgehog, leader of the Black Arms who wants to conquer Earth. He claims to be immortal, but the truth is he can be killed by his own power. His minions would never turn on him, but Shadow was created with his blood. Shadow turns Super Saiyan and hits him in the eye with Chaos Spear. Once defeated, Black Doom cries out in disbelief that this could happen and, with a dying groan, falls, and is never seen again.
Babylon Guardian
The evil genie guarding the treasure of Babylon Garden, and final boss of Sonic Riders. Sonic smashes his bottle, and he fades away with sparkles, leaving only the treasure. (Remember Return of Jafar, what happens when you destroy a genie's container)
Master Core: ABIS
The main villain and final boss of Sonic Riders: Zero Gravity. He opens a black hole with the intent of destroying the earth, but Sonic engages him in a death race and hits him with Gravity Dive. ABIS explodes in a spectacular explosion, and the black hole closes.
Captain Whisker
The main villain of Sonic Rush Adventure. When Sonic and Blaze blow up his giant robot, Captain Whisker, the explosion sinks his ship while Sonic and Blaze jump into the water, Blaze mentions that the pirates sank, and that they're "gone" so they can't have stolen the Jeweled Scepter a second time, meaning Whisker was killed in the blast.
Iblis and Mephiles the Dark
Somehow people pounced on the Archie comics to say they survived, but their deaths should be the most definite of the series. These villains of the universally loathed Sonic 06 merge into Solaris, and once defeated, time turns back to when Solaris was a flame, before he split into Iblis and Mephiles. Elise blows out the flame, thus erasing the events of the game, set in motion by Iblis and Mephiles, from history, since they no longer exist.
(The Archie comics are a separate universe so they have no power over the games' main canon, look what happened with Metal Sonic there)
Ifrit
The final boss of Sonic Rivals 2 whom Eggman Nega plans to unleash to bring hell on earth. Once defeated by Shadow and Metal Sonic, as I suspect they're the last to fight him, he falls and explodes in a fiery explosion.
Eggman Nega
This one is the one I think could have possibly survived because his fate was never confirmed. But last we saw him, in Sonic Rivals 2, his legs were caught under some rubble (sent falling by the Ifrit), abandoned by Silver and Espio (whom he turns to for help indicating that Metal Sonic 3.0 has been destroyed or else he'd have turned to him first), and Shadow and Metal Sonic close the portal to the Ifrit's dimension, which can only be opened with the Chaos Emeralds, and will probably die of dehydration in there coz it's so hot (otherwise, starvation).
Unless there's someone we don't know about who breaks him out within probably days after he's trapped there, I'll say his time is up, and we've never seen him since. But Metal Sonic 3.0 presumably released him from a card, so if they wanted to bring him back, they could.
Dark Gaia
The main villain (besides Eggman) and final boss of Sonic Unleashed, Sonic fights him and in the end, whichever version you go by, he plows through his center eye. Green blood gushes from him as he rapidly decays, falling back into the lava from whence he appeared. (We know lava can't kill him, but I think Sonic's attack did)
This is debated because Professor Pickle comments about the balance between light and dark, saying the darkness may have been laid to rest instead of destroyed. Although, my theory is, though Dark Gaia is dead, his essence remains in a disembodied state.
Metal Sonic
This is the most highly debated one. In Sonic Generations, Metal Sonic challenges Classic Sonic to a death race for a Chaos Emerald. They visit the bad future of Stardust Speedway in Sonic CD and race, ending with Classic Sonic kicking Metal Sonic into the air, where he explodes. He's never seen again in any cutscenes, not even cheering for Eggman in the final battle where Shadow and Silver appeared to cheer for Sonic.
People insist he survived for a number of reasons:
- First and foremost, he continues to appear in White Space for a rematch, with different dialog. (My counter is that it's non-canon and just a way of giving the player the freedom to fight him again, or possibly even rewound if you think they are canon, and the extra dialog is like how dialog changes for Sirius appearances in Bomberman 64, when canonically, neither Bomberman nor Sirius revisit the levels, but the players can).
- Second, that he can just be rebuilt. (Counter: Unlike in Sonic CD, where his body was intact, there was nothing left of him this time)
- Third, it's his Classic self. (Two possible counters: 1.) He reverted to this physical form for the occasion, remembering fighting Sonic there before, though retaining his usual powers. He has liquid metal shapeshifting, demonstrated in both Sonic Heroes (even becoming a super-upgraded Neo Metal Sonic) and Sonic Free Riders. 2.) It was his past self, and, while not altering past events, sorta merges with the present once the timeline is restored, causing him to disappear. Kinda like Demise from Skyward Sword)
The Deadly Six
This is the second most debated one, even though people disliked them. The villains of Sonic Lost World jump away the first two times they are defeated. The third, Zazz, Zomom, Zik, and Zeena explode in a puff of smoke, Super Mario Galaxy style, and Zor and Zavok fall into lava.
People want to believe they survived so badly they say the first four teleported away, and the other two are immune to lava. But the Deadly Six have never displayed teleportation powers (they jump/fly away the first time, remember), and Zor's final words indicates he's about to die, which he disturbingly welcomes as he's Emo.
What makes people think they survived is Eggman planning to control them again, even though he was working on his robot at the time of their "deaths" and could not have possibly seen how the battles ended. (Like in Soul Eater, Giriko says he'll kill Arachne, only to be informed by Justin Long that she's already dead). Yet they weren't shown after their defeat, while Eggman was, to let us know he survived his fall.
This is in the Wii U version, in the 3DS version they unambiguously survive, so if they reappear in any game, it's either in the Sonic Boom universe (as I understand Zazz does), some non-canon spinoff like Olympics, or set in 3DS continuity.
...
So, say what you think of their status there or not.
And don't give me any of the "It's too kid-friendly to kill even a villain" stuff. Kid-friendlier shows than this have killed villains. Two generations of My Little Pony have done it, though even though the writer of the second one pronouncing him dead hasn't stopped people from debating it