Source

File: wp-includes/author-template.php

function get_the_author( $deprecated = '' ) {
	global $authordata;

	if ( ! empty( $deprecated ) ) {
		_deprecated_argument( __FUNCTION__, '2.1.0' );
	}

	/**
	 * Filters the display name of the current post's author.
	 *
	 * @since 2.9.0
	 *
	 * @param string|null $display_name The author's display name.
	 */
	return apply_filters( 'the_author', is_object( $authordata ) ? $authordata->display_name : null );
}