I don't think Horcruxes count - it's introduced way later in the series where we're already very deeply invested in all the characters, and instead of disappear

I don't think Horcruxes count - it's introduced way later in the series where we're already very deeply invested in all the characters, and instead of disappearing, it becomes the center of the attention for the rest of the series. So, in a sense, I'd call it an anti-MacGuffin.