Queen Novo, Prince Rutherford, King Thorax, Dragon Lord Ember, & Gilda. These are the five ambassadors of their respective kingdoms; Mount Aris, Yakyakistan, the Changeling Hive, the Dragon Lands, and Griffonstone. While these five creatures are all ambassadors, they really haven’t spent time with each other. Twilight has an idea to invite them all to Canterlot to see if they could break the ice. Needless to say, they do learn more about their species.
Idea from this picture and this picture.