Casper Holstein (December 7, 1876 – April 5, 1944) was a prominent New York mobster involved in the Harlem "numbers rackets" during the Harlem Renaissance. He, along with his occasional rival Stephanie St. Clair, was responsible for bringing back illegal gambling to the neighborhood after an eight-year absence following the conviction of Peter H. Matthews in 1915. Holstein became known as the "Bolito King".