OK, just for fun, here's the idea.
You're hosting dinner for four. You and 3 other people. ANY people, living or dead. And they will all show up. And any of them who don't speak English will magically learn it on their way.
So.... who's coming to dinner?
My choices:
Bertrand Russell
Gottfried von Leibniz
Albert Einstein
Why these three?
First, not only are all three brilliant, they all loved to talk. And they all were good at talking to normal people.
Bertrand Russell (1872-1970) was a philosopher and protested against both WW I and Vietnam (that has to be a small group!). He wrote many books, both popular and scholarly, and gave a much more coherent reasoning for being an atheist than the modern anti-theists.
Leibniz (1646-1716), co-inventor of the calculus (with Newton) was so smart that he was (per Neal Stephenson, anyway) known as "il monstro" - the monster. He was not only one of the greatest mathematicians, but also a lawyer, philosopher and inventor. He contributed to fields that became biology, medicine, geology, probability, statistics, psychology, linguistics and computer science, and wrote books on law, politics, history, philosophy and philology.
And Einstein was Einstein (1879-1955). A stunningly brilliant physicist, he was also a pacifist, a philosopher and a master of a good quote.
So, who's eating at your house? (added) And why?