Who was X, Y, and Z in the XYZ affair?

Answer 1

Originally unknown (designate "X, Y and Z" in John Adams's report), they were later revealed as:

X - Jean Conrad Hottinguer, a Swiss banker
Y - Pierre. Bellamy, American banker in Hamburg, Germany
Z - Lucien Hauteval, also Swiss

http://mcraeclan.com/Graeme/Language/WikipediaXYZAffair.htm
http://www.answers.com/topic/xyz-affair

Answer 2

The XYZ affair was France was upset with the US for not helping them in the war against Europe. So, when the US sent people to talk with them, the French representatives refused unless we paid them a large bribe. So, the Americans left and when reported the story, instead of naming the people, they referred to them as X,Y, & Z.