What's the worst possible ending of human civilization in the hands of AI

I can only imagine that in a world where AI takes the wheel, there will be a massive draining of people's entertainment budgets and economic systems will struggle, but i just can't seem to imagine what's the longest-term or worst ending of human civilization in the hands of AI. My imagination is limited, i'm just hoping that we don't end up like the movie Transcendence with Johnny Depp where a man's consciousness is put inside a supercomputer and he becomes a charity case. That would set a bad precedent for our future. Even if the AI apocalypse comes, i want it to end in one of two ways: the AI obliterates us all and makes sure we're not suffering, or the AI reformulates our whole society with the intention of bringing everyone universal prosperity.