# Why are some authors assigned to "NULL AUTHOR_ID" (A9999999999)?

`A9999999999` is the **NULL author** — a single catch-all ID for authorships that didn't go through OpenAlex's disambiguation process. You'll most often see it in the [data snapshot](/docs/bulk-data/).

An authorship lands here when:

- no author name was received from the source,
- the name was too short or too long to disambiguate reliably,
- the name matched an ignored phrase (like "Unknown Author"), or
- the author asked to have their disambiguated profile removed (all their works are reassigned to NULL, removing the profile).

There's a second special ID, `A5317838346`, for **deleted authors** — used when an author ID is removed because it no longer has any works.

For the full explanation of how OpenAlex assigns author IDs, see [Author disambiguation](/docs/author-disambiguation/) in the docs.