Isabel Ecclestone Mackay (1875-1928) was a Canadian poet, playwright and novelist. She was born in Woodstock, Ontario. She received her education in Ontario and moved to Vancouver along with her husband, Peter J. Mackay, in 1909. There she wrote all her major works. She is the author of several novels, a book of lyrics, and a volume of poems for children. Her play Treasure (1926) won the open, all Canadian I.O.D.E. Contest in 1926.