Robert Leslie Carroll Conly (January 11, 1918 – March 5, 1973), better known by his pen name Robert C. O'Brien, was an American novelist and a journalist for National Geographic magazine. He is best known for his 1971 children's novel Mrs. Frisby and the Rats of NIMH, which was adapted to the 1982 animated film The Secret of NIMH directed by Don Bluth.
Source: Wikipedia