No one person gets all the credit for developing the scientific method because it was developed over thousands of years, by many different scientists, starting with Aristotle. It has continued to develop and is the general method for all branches of science.
Aristotle gave science the basis for the scientific method. He wanted to find a way to be sure the information he came up with was always reliable. In the 13th century, Roger Bacon developed a system by which observation, hypothesis, experimentation and verification became the norm. Galileo took this one step further and introduced mathematical deduction and confirmatory experiments into the scientific method.
Since then, several scientists including Descartes, John Locke, Albert Einstein and Michael Faraday have all contributed to the continuing development of the scientific method.