Sidney Mason Stone (May 8, 1803 – August 10, 1882) was a prominent Connecticut architect and builder known for designs of churches, institutional buildings and residences. His creations incorporated Greek Revival, Romanesque, Gothic, Italianate and other styles popular in the 19th century. He served in several civic capacities in the city of New Haven and statewide and as mentor to Yale students prior to the establishment of that university's School of Architecture. He was the father of Harriet Mulford Stone, better known to readers of children's literature as Margaret Sidney, creator of the Five Little Peppers series.