User:SOTO/Forum Archive/The Reference Desk/@comment-24894325-20160526133608/@comment-1432718-20160526141804

To quote from Tardis:What categories are not: "Categories are not a substitute for writing the article. Don't add a category to a page unless you've justified that addition in the text of the article itself."

So in this case, if there is no story evidence that someone was alive and present on Earth (since centuries are based on Earth dating) during a particular century, we don't add the category.

Think about it this way: this is Doctor Who. Anything can and will happen (and probably already has). One day some author might write a story about some immortal being off-Earth for a particular century, in which case the character would not belong in the category for that century.