American Champion Three-Year-Old Filly

The American Champion Three-Year-Old Filly is an American Thoroughbred horse racing honor awarded annually to a female horse in Thoroughbred flat racing. It became part of the Eclipse Awards program in 1971.

The award originated in 1936 when both the Daily Racing Form (DRF) and Turf and Sports Digest (TSD) magazine began naming an annual champion. Starting in 1950, the Thoroughbred Racing Associations (TRA) began naming its own champion. The following list provides the name of the horses chosen by these organizations. There were several disagreements, with more than one champion being recognized on five occasions. In 1949, two Calumet Farm fillies, Wistful and Two Lea, shared the Champion's title after finishing equal top of the Daily Racing Form poll.

The Daily Racing Form, the Thoroughbred Racing Associations, and the National Turf Writers Association all joined forces in 1971 to create the Eclipse Award. In 1978, the voting resulted in a tie between two fillies.

Champions from 1887 through 1935 were selected retrospectively by a panel of experts as published by The Blood-Horse magazine.