Talleyrand - A brilliant and machiavelic French diplomat. He was already active before the French revolution, and managed to stay in high positions (including Minister of Foreign affairs under Napoleon) until the 1815.
Among others, he worked on the declaration of Human Rights, the coup d'état of Napoleon, the Vienna conference, ... He even participated at the partitioning of the Low Countries in 1830.
Fascinating guy really. Without him Europe would be very different nowadays.