Wordpress Query Parameters Author Parameter

Display posts by author, using author id:
$query = new WP_Query( array( 'author' => 123 ) );

Display posts by author, using author ‘user_nicename‘:
$query = new WP_Query( array( 'author_name' => 'rami' ) );

Show Posts From Several Authors
Display posts from several specific authors:
$query = new WP_Query( array( 'author' => '2,6,17,38' ) );

Exclude Posts Belonging to an Author
Display all posts except those from an author(singular) by prefixing its id with a ‘-‘ (minus) sign:
$query = new WP_Query( array( 'author' => -12 ) );

Multiple Author Handling
Display posts from multiple authors:
$query = new WP_Query( array( 'author__in' => array( 2, 6 ) ) );

You can also exclude multiple author this way:
$query = new WP_Query( array( 'author__not_in' => array( 2, 6 ) ) );