On the Post edit page in the back-end, how do I echo the author's
user_nicename? I am referring to the author of the post, not current user.
global $post; $author_id=$post->post_author; the_author_meta('user_nicename', $author_id );
Came across this because I needed to do this, I would advise against accessing the global like this I used this.
get_the_author_meta( 'user_nicename', get_the_author_meta( 'ID' ) )