Cecily Wilhelmine Ullmann Sidgwick (1854 – 10 August 1934) was a British novelist. She published 45 novels, mostly about the Jewish experience in England and Germany, under the names Mrs. Alfred Ullmann Sidgwick and Andrew Dean.
Cecily Wilhelmine Ullmann was born in 1854 in Islington, London to German-Jewish parents, David Ullmann and Wilhelmine Auguste Flaase Ullmann. In 1883, she married Alfred Sidgwick, logician and philosopher at Owens College in Manchester.
Most of her novels dealt with the marriages of middle-class Jewish families, and she touched on subjects including anti-Semitism, interfaith marriage, and suicide.
Cecily Sidgwick died on 10 August 1934 in St Buryan, Cornwall.
