Ruy López de Segura was a Spanish chess player and writer, born around 1530. He is often regarded as one of the first chess professionals and made significant contributions to the game. His most famous work, "Libro de la invención liberal y arte del juego del ajedrez," published in 1561, laid the foundation for modern chess theory. López is best known for the Ruy López opening, a popular chess opening named after him. His strategies and analyses helped elevate chess from a pastime to a respected intellectual pursuit. He played a crucial role in popularizing chess in Europe during the Renaissance.