Not only PHP but probably the database too, unless you want the names hardcoded.
If hardcoded, you might be able to do something like...
<?php
$names = ['Andrex', 'demi', 'Oblivion'];
echo '<select id="author" name="author">';
foreach ($names as &$val) {
echo '<option value="' . $val . '">' . $val . '</option>";
}
echo '</select>';
?>
You could replace the author input/label in the comments form with this, if it worked. Count it as pseudocode.
But don't hold me to that, I'm not super familiar with PHP (ironically most of my knowledge of it comes from making WP themes, lol.)
