Our story begins with an elite assassin. He was genetically engineered from conception to be the perfect killing machine, and is known only by the last two digits on the barcode tattooed on the back of his neck. He is the culmination of decades of research - and forty-six earlier Agent clones - endowing him with unprecedented strength, speed, stamina and intelligence. Creating the PERFECT killer requires him to be more than just human. It requires some magic in the mixture. This is the story of 47.
Note: As the agents are clones they are detected, by magic as being the same person. Because they were made, not born, all are detected as being the origional donor. I am going to suggest you use Gellert Grindlwald. The agency would want someone powerful, and a few drops of blood is a cheap payment for the use of some assassins, particularly if he used magic on his blood first, with the intention of subverting the Agents.