Final answer:
The Greek philosopher known for the concept of atoms is Democritus. He introduced the idea of 'atomos,' indivisible entities making up all matter, which contrasted with the monistic views of other philosophers of his time.
Step-by-step explanation:
The ancient Greek who is known for championing the concept of atoms was Democritus. Democritus, often referred to as the 'laughing philosopher' for his emphasis on cheerfulness, proposed a theory that was radically different from the prevailing thoughts of other early Greek philosophers. Around 2,500 years ago, he suggested that all matter in the universe was made up of tiny, indivisible, solid objects he called 'atomos' or 'atomon'. This idea was contrary to the belief that all substances were part of a single, unchangeable entity. Despite the initial dismissal of Democritus's theory by Greek philosophers who favored logic and reason over experiment and observation, his concept of atoms laid the groundwork for what would centuries later become a fundamental aspect of modern scientific understanding.