The scientist known for the theory of evolution is Charles Darwin. His groundbreaking work, "On the Origin of Species," published in 1859, introduced the concept of natural selection as a mechanism for evolution. Darwin proposed that species evolve over time through a process in which individuals with favorable traits have a better chance of survival and reproduction. This theory revolutionized the understanding of biological diversity and the interconnectedness of life forms, challenging existing beliefs about the fixed nature of species. Darwin's ideas laid the foundation for modern evolutionary biology and continue to influence scientific thought today.