How many named Nine Titans are there in Attack on Titan's core mythology?

How to get close to this number

The name gives it away, exactly as the decathlon does. When a work names a group with a number in the title, the count is not something to recall — it is something to read. This is worth internalising because fiction does it constantly, and half the questions of this kind answer themselves.

The trap is that the story is populated by far more titans than the named ones. Most are anonymous, and a viewer counting creatures rather than named powers would arrive at a number with no relation to the answer. The question asks about the core mythology specifically, which is a much narrower category than what appears on screen.

The mechanism in the explanation is what makes the count stable: each power passes to a new holder when the current one dies, so the number of powers stays fixed while the number of characters who have held them grows. That is an elegant way to keep a fixed roster in a story where characters keep dying, and it is why the count never drifts upward.