WordPress at a glance
filter is not described

the_author filter-hook . WP 2.9.0

Filters the display name of the current post's author.

Usage

add_filter( 'the_author', 'filter_function_name_4894' );
function filter_function_name_4894( $display_name ){
	// filter...

	return $display_name;
}
$display_name(string)
The author's display name.

Where the hook is called

get_the_author()
the_author
wp-includes/author-template.php 37
return apply_filters( 'the_author', is_object( $authordata ) ? $authordata->display_name : null );

Where the hook is used (in WP core)

wp-includes/default-filters.php 228
add_filter( 'the_author', 'ent2ncr', 8 );