History of science
The English word scientist is relatively recentfirst coined by William Whewell in the 19th century. Previously, people investigating nature called themselves natural philosophers. While empirical investigations of the natural world have been described since classical antiquity (for example, by Thales, Aristotle, and others), and scientific methods have been employed since the Middle Ages (for example, by Ibn al-Haytham, and Roger Bacon), the dawn of modern science is often traced back to the early modern period and in particular to the scientific revolution that took place in 16th- and 17th-century Europe. Scientific methods are considered to be so fundamental to modern science that some consider earlier inquiries into nature to be pre-scientific. Traditionally, historians of science have defined science sufficiently broadly to include those inquiries.

Q: Ibn al-Haytham and Roger Bacon were scientists in which time period?
the Middle Ages