Index: src/wp-includes/author-template.php
===================================================================
--- src/wp-includes/author-template.php	(revision 31306)
+++ src/wp-includes/author-template.php	(working copy)
@@ -72,7 +72,7 @@
  *
  * @return string The author's display name.
  */
-function get_the_modified_author() {
+function get_the_modified_author($field = 'display_name') {
 	if ( $last_id = get_post_meta( get_post()->ID, '_edit_last', true) ) {
 		$last_user = get_userdata($last_id);
 
@@ -83,7 +83,7 @@
 		 *
 		 * @param string $last_user->display_name The author's display name.
 		 */
-		return apply_filters('the_modified_author', $last_user->display_name);
+		return apply_filters('the_modified_author', $last_user->$field);
 	}
 }