Anna Constantia Thynne, Lady John Thynne (née Beresford; 1806–1866) was a British marine zoologist. In 1846, she built the first stable and sustained marine aquarium and maintained corals and sponges in it for over three years. In 1847 she added marine plants to the bowls, and in two years had created the first balanced marine aquarium. Thynne’s work inspired Philip Henry Gosse, who developed the Fish House at London Zoo in 1853.