Who is the father of calculus?

Sir Issac Newton and Gottafried Wilhelm Leibniz are the father of calculus. Newton discovered Calculus during 1665-1667 and is best known for his contribution in the Physics and the discovery of three laws of motion whereas, Leibniz was best known for introducing notations like dy/dx, integral symbol which are still in use through out the world. Besides Newton and Leibniz there are some unforgettable contributors like Pythagoras, Kevin, Archimedes etc.