A theoretician is an individual who specializes in the theoretical aspects of a particular field. They are often experts in their field and use their knowledge to develop theories, analyze data, and provide insight into complex problems. Theoreticians are often found in fields such as mathematics, physics, engineering, and computer science. They are also found in other areas such as economics, psychology, and sociology. Theoreticians are highly knowledgeable and often have a deep understanding of the subject matter they are studying.