Deadpool speaks for himself (well not ALL of the time) he would be the life of the party, he would kill it on the dance floor, literally. And if that weren't enough he would probably smuggle in Spidey, most likely against his will, as a bonus.
Now Thor has that perfect mix between the jolliness of the big guy in the red suit, old Saint Nic and the wildness of that party ANIMAL we all know. He is not just the prince of Asgard he is the king of party tricks!
3. Michael Bay
I know he may not be the most loveable person on the planet right now for all the movies and such but imagine this almost everyone is here but miche-...*roof comes flying off and there are flares and explosions everywhere* It all goes quiet and he rappels down from the heavens, high fives you and sits down quietly as if that's his morning routine (it probably is) that would certainly break the ice.
4. Robin Williams
The man is a legend. This comedy GENIUS would have every one huddled together at the end of the night to hear one of his brilliant stories which he so cleverly made up on the spot. Rest in piece you absolute legend you will be missed.
5. Samuel L. Jackson
This man is the definition of badass. He is the guy that brings a cold case of beers to the party being fashionably late and leaves with the spares and God help you if you ask him to leave them he'll unleash a while new work of pain upon the large watermelon on the plateau of your shoulders.
Bill Nye the Science Guy *BILL BILL BILL BILL BILL*