https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#4xx_...
This was famously used by Mark Pilgrim:
https://en.wikipedia.org/wiki/Mark_Pilgrim#%22Disappearance%...
> Who knew there were so many different status codes.
As an HTTP nerd, the authoritative listing of the different codes is: https://www.iana.org/assignments/http-status-codes
Note: Everything with a reference that's not RFC 7231 is an extension; don't use that status code unless you actually implement that extension. For example, don't use 401 (Unauthorized) instead of 403 (Forbidden) unless you actually implement the RFC 7235 Authentication extension.
Edit--added note
[1] For all the good it does. I just checked my logs and I still see requests for pages I marked as "gone" 15 years ago.
News sites could also replace their 404 page with an explanation "there used to be an article here, but we decided to remove it because ____" or "there's never been an article at this address".