Gustave E. Steinback (1878–1959) was an American architect practicing in New York City in the early and mid twentieth century.

The firm, known as Reiley and Steinback continued in practice from 1904 through 1913 and was responsible for many buildings for Roman Catholic clients throughout the Eastern United States.

[3] After the partnership was dissolved, both men went on to lengthy careers designing Roman Catholic churches.

[1] Steinback was active in civic affairs and was for many years a member of the Stamford City Planning Board.

[5] Unlike many other of his contemporaries, Steinback continued to work in private practice during World War I, not completing any government service until World War II when he worked on engineering on Stewart's Field and at Rye Lake Airport.