Peter Berresford Ellis (born 1943) is an Irish author and historian, best known for his works on Celtic history and culture. He has written extensively about the Celtic heritage of Britain and Ireland, focusing on various aspects including language, mythology, and the historical context of the Celtic people. Ellis has published numerous books, both fiction and non-fiction, and is recognized for his efforts to promote and preserve Celtic languages and traditions. His work often emphasizes the importance of understanding Celtic history in the context of broader European history. If you would like more specific information about his books or contributions, feel free to ask!