William Mitcheson Timlin (11 April 1892 - 1943) was an architect and illustrator. He was born in Ashington, Northumberland. In 1912, he joined his parents in South Africa where he completed his training in art and architecture and remained for the rest of his life.
Timlin worked on The Ship that Sailed to Mars for two years. It was started as a diversion for his son in 1921. The work expanded until in its final form it had 48 pages of text and 48 colour plates showing remarkable flights of fantasy.
William M. Timlin ranks alongside Dulac, Rackam, and Pogany as one of the greatest children's fantasy illustrators, despite his having published only one book in his lifetime (The Ship that Sailed to Mars, 1923). He died before his second great work, The Building of a Fairy City could be completed.