User blog comment:HazelQuill7445/Awesome fan art/@comment-25936766-20180704225950/@comment-10380701-20180705045232

Nikola Tesla is the absolute youngest servant you can summon allegedly. Which is a good contrast with Gil, the oldest servant summonable.

But in 2030 you can potentially summon Neil Armstrong too.

Mr. Rogers would probably be an amazing Ruler since he's a nice guy.