Walter Farrell, OP (b. Chicago, IL July 21,1902; d. River Forest, IL November 23, 1951), was a prominent Central Province moral theologian, instrumental in developing theology for the laity. He combined the life of an active preacher with that of doing both speculative and popular theology.

He helped to launch the Thomist, a quarterly specultive review, in April 1939, and contributed to it and to other leading Catholic journals. He is especially known for his Companion to the Summa, the four volumes which were published from 1938-1942.