The famous physicist known for his work in electromagnetism is James Clerk Maxwell. His groundbreaking contributions came in the 19th century, particularly with the formulation of Maxwell's equations, which describe the behavior of electric and magnetic fields and their interactions with charged particles. These equations laid the foundation for modern physics and were pivotal in the development of technologies like radio, television, and lasers. Maxwell's work not only unified various branches of physics under the umbrella of electromagnetism but also paved the way for later scientists, including Einstein, to develop theories about light and relativity.