Comparison of various wars

[Batman]

Well if you want to settle for 'okay, not exactly extinct, but the humans certainly got their teeth kicked in' there's both BSGs, Titan A.E. and Zahn's 'Blackcollar' books (no, mankind is nowhere near extinction, but they were in a total war and lost before the story even starts).

[TithonusSyndrome]

Stories where humankind gets a kick in the teeth are a dime a dozen, but virtual extinction scenarios are much more relevant here and I'm surprised nobody's mentioned Adventure Time yet as the primary one.

[Cykeisme]

Re-reading the OP question, it seems we might need to clarify which we consider worse:

- More humans killed
- Fewer humans remaining

In my opinion the latter is worse. If one hundred trillion humans are killed in a war, but there are one hundred trillion remaining after the war ends, the casualties were horrific, but humanity trudges on, possibly to become ascendant once more.
In the latter, even if only seven billion humans were killed, there are zero left.


Anyway, if it's the latter, then NecronLord and TithonusSyndrome's suggestions are likely the worst (although those works might make it unclear whether it was disaster or war that led to the result), because there are no human beings remaining.

[Cykeisme]

Stories where humankind gets a kick in the teeth are a dime a dozen, but virtual extinction scenarios are much more relevant here and I'm surprised nobody's mentioned Adventure Time yet as the primary one.

Good lord, I thought it was a light-hearted cartoon. I know very little about it. What's the premise for Adventure Time?

[Imperial Overlord]

Charles Stross's Saturn's Children books take place in a future where humanity is extinct. The main characters are robot AIs.

[Borgholio]

Wouldn't the AU of Enterprise count? The Xindi had destroyed Earth and it was implied that the only surviving humans were settled on Ceti Alpha 5, which was going to be destroyed anyways either by a Xindi bombardment or blow itself up in a hundred years anyways (Star Trek 2).

[NecronLord]

What about science fiction that doesn't have a central human faction?

I mean, take Star Wars: it has humans in abundance, but their is no all-human faction (although the society as a whole appears to be human-dominated, particularly the Galactic Empire). That one would have to be high up if it counts though, for the Galactic Civil War and Clone Wars. They weren't civilization-destroying or anything, but given how big the galaxy is, the scope and the death toll must have been gigantic.

Or for a still-less human-centric example, its damn hard to top the Last Great Time War from Doctor Who. Humans were certainly affected, greatly, by the conflict and its aftermath, as well, but the primary combatants were aliens (the Time Lords and the Daleks).

I should note that the largest attack in the Time War (that we know about!) is also from the Dalek Empire series, or rather from one of the proto-episodes, The Apocalypse Element which was mentioned by Russel T Davies as one of the early spasms of the Time War.

The Daleks destroy Galaxy 17A53, AKA Seriphia, four times the size of the Milky Way and inhabited, using a conceptual cousin of the Reality Bomb, and force the Time Lords to contain the 'blast' by reverting the entire galaxy to a primordial state, which they then leave to colonize. But it's unlikely the inhabitants were human.

an entire galaxy four times larger than the Milky Way is burning as they speak, six hundred billion stars and an unimaginable number of lives have already been lost, and if they cannot contain the firestorm then it will spread out until nothing is left, anywhere.

[Bedlam]

Stories where humankind gets a kick in the teeth are a dime a dozen, but virtual extinction scenarios are much more relevant here and I'm surprised nobody's mentioned Adventure Time yet as the primary one.

Good lord, I thought it was a light-hearted cartoon. I know very little about it. What's the premise for Adventure Time?

It seems to be set in a fairly weird fantasy world but once you look a bit more closely it's a post apocalyptic world, most of civilisation was destroyed in the 'mushroom war' about a thousand years ago most of the new civilisations seem to be uplifted creatures, other dimensional / alien creatures or constructs. Although there are a fair number of (mostly) humanoid creatures about there are only really a handful of humans around and most of them are altered in some way or another.

The planets been seen from space and there's a crater taking up about a quarter of the globe and many of the wilderness areas seen have various relics of the destroyed civilisation lying around here and there.

[TithonusSyndrome]

Stories where humankind gets a kick in the teeth are a dime a dozen, but virtual extinction scenarios are much more relevant here and I'm surprised nobody's mentioned Adventure Time yet as the primary one.

Good lord, I thought it was a light-hearted cartoon. I know very little about it. What's the premise for Adventure Time?

It seems to be set in a fairly weird fantasy world but once you look a bit more closely it's a post apocalyptic world, most of civilisation was destroyed in the 'mushroom war' about a thousand years ago most of the new civilisations seem to be uplifted creatures, other dimensional / alien creatures or constructs. Although there are a fair number of (mostly) humanoid creatures about there are only really a handful of humans around and most of them are altered in some way or another.

The planets been seen from space and there's a crater taking up about a quarter of the globe and many of the wilderness areas seen have various relics of the destroyed civilisation lying around here and there.

To expand, Finn the Human is the only full and proper human being remaining on the planet Earth; there are only partial exceptions in the form of ex-humans who are on some kind of highly specific life support or cybernetic augmentation beyond recognition, and even these amount to no more than a small handful scattered distantly across the wastes of the planet. Finn has no idea who his parents are, as he was discovered abandoned at birth by the family of Jake the Dog, and the implication at present is that he will be the final human being to ever be.

[Cykeisme]

I will feed my newfound interest in Adventure Time.

[Bedlam]

I will feed my newfound interest in Adventure Time.

Well the actual background doesn't come up that often although it's interesting when it does.

Most of the time it's very strange and surreal.

Although I would still recommend it, I'm working my way though season 4 at the moment although I've just found out the UK season 2 box set I have is missing four episodes including about the only two which actually have continuity to things that happen later, which explains why somethings relating to Princess Bubblegum seem to come out of nowhere.