Old School: Aristotle and Archimedes
Aristotle is considered by many to be the first true scientist. His primary interest was biology and wrote extensively about marine biology and taxonomy (animal classification). He also proposed that celestial bodies moved in circles at constant velocities. This, of course, was incorrect assumption, but a critical step in the history of astronomy. Archimedes was a mathematician and inventor whose innovations included conic sections, the area of circles, the physics of levers, and displacement of floating bodies. He was also the inventor of many devices including the Archimedes screw, a sun based heat ray (probably not a real invention, but it sounds cool (and hasn’t actually been completely disproved)) ,and a water based clock.
New School: James Watson and Francis Crick
Watson and Crick are best known for proposing the double helix model of DNA in 1953 by using x-ray crystallography. They are also the pioneers of the Watson-Crick nucleotide pairing model. This model describes how certain nucleotide sequences are paired with a specific nucleotide sequence. They won the 1962 Nobel Prize in Physiology or Medicine for their discoveries and their research created the revolutionary field of genetic biology.