Source

File: wp-admin/includes/meta-boxes.php

function post_author_meta_box( $post ) {
	global $user_ID;
	?>
<label class="screen-reader-text" for="post_author_override"><?php _e( 'Author' ); ?></label>
	<?php
	wp_dropdown_users(
		array(
			'who'              => 'authors',
			'name'             => 'post_author_override',
			'selected'         => empty( $post->ID ) ? $user_ID : $post->post_author,
			'include_selected' => true,
			'show'             => 'display_name_with_login',
		)
	);
}