We already have another thread ik, but this is speaking only book/Fantastic beasts screenplay canons. Here is my list
Credence (potentially rivals number 1)
Honorable mentions: The deathly hallow brothers if they truly created the Hallows, Death itself if the story is true (number 1 really) other school founders.
__________________ "Vader's pulse and breathing were machine-regulated, so they could not quicken; but something in his chest became more electric around his meetings with the Emperor; he could not say how. A feeling of fullness, of power, of dark and demon mastery -- of secret lusts, unrestrained passion, wild submission -- all these things were in Vader's heart as he neared his Emperor. These things and more."