text: They were created by Dr. Kit Pedler ( the unofficial scientific advisor to the program ) and Gerry Davis in 1966 , first appearing in the serial The Tenth Planet , the last to feature William Hartnell as the First Doctor .
simplified: They were created by Dr. Kit Pedler ( the unofficial scientific advisor to the program ) and Gerry Davis in 1966 , first appearing in the serial , The Tenth Planet , which was the last to feature William Hartnell as the First Doctor .