The first Nobel Prizes were awarded in 1901, while Sir Isaac Newton died in 1727. But if the prizes had been around during his lifetime, he would have won it hands down in multiple years.
Einstein is renowned for his imagination and ability to intuitively lay out new conceptual models of the universe. Newton's talents were different. His unparalleled logical and mathematical genius allowed him to formulate observations into laws and to prove ideas through rigorous mathematics. When the mathematical machinery he needed didn't fully exist, he invented it. That's what largely inspired RealClearScience Editor Alex Berezow to name Newton the smartest person who ever lived.
While Einstein's physics are still being proved today, Newton's is so monumental, so important, so fundamental, so proven within its realm of validity, that scientists of every sort take it for granted every day. The laws of gravity and motion that Einstein reenvisioned were edits of the commandments first called down from the ether by Newton's blinding brilliance.
Newton formulated laws of physics, and worked in optics and astronomy, too. He was also named Warden of the Mint, and introduced monetary safeguards that would have won a Nobel Prize in Economics as well. Tom Hartsfield figures he could have won up to eight Nobels for his life’s work, and that doesn’t even count inventing the cat flap. However, those don't take into account who his competition would have been in those particular years, which would be an extensive project for someone so inclined. Read about each of Newton's possible Nobels at Real Clear Science.