The Great Intelligence, also known as "Yog-Sothoth", is an entity who has been among the Doctor's many enemies in the series Doctor Who. However, while introduced in the 1967 episode "The Abominable Snowmen", the Great Intelligence's origins are revealed in the 2012 episode "The Snowmen" and he acts as the main antagonist of season 7 of the new series. He was voiced by Ian McKellen in "The Snowmen", and was portrayed by Richard E. Grant (who initially played his host, Walter Simeon) for the rest of the series.