Is there a "hook_user_login_failed" hook? Or something similar? I'm needing to detect when a login failure happens in Drupal and am finding it to be exceedingly difficult even after searching Google.  I have to believe this exists somewhere.

I found this post back from 2007 which seems like an entirely reasonable request for a "failed login" hook: https://www.drupal.org/node/160469 Is there something that allows this?

Thanks in advance.

AG3
At least in Drupal 7, there is no hook for that.  The login form uses validators, one which authenticates, and another that follows and sets a form error if login failed.  

One option would be to add a custom validator to the form using hook_form_FORM_ID_alter, and check the status of login there.  See user_login_final_validate in user.module for an example of how status is checked.