Born in 1841, son of Washington and Ella Thompson McClintock. He graduated from Yale in 1862 and was associated with this brother Frank McClintock in O. McClintock and Company, a mercantile house. Brother Oliver McClintock was president of this company.
Walter was a charter member of the South Fork Fishing and Hunting Club.
He married Mary Garrison and their children included: Evan Garrison McClintock (1868); Abraham Garrison McClintock: and C.O. McClintock. Walter and Mary resided at 929 Ridge Avenue, Allegheny, PA. However, they made their summer home at Castine, ME and winter home at Ornand, FL.