Kate Douglas Wiggin (September 28, 1856 - August 24, 1923) was an American children's author and educator.

Kate Douglas Smith Wiggin was born in Philadelphia, and was of Welsh descent . She started the first free kindergarten in San Francisco in 1878 (the "Silver Street Free Kindergarten"). With her sister in the 1880s she also established a training school for kindergarten teachers.

She was also a writer of children's books, the best known being The Birds' Christmas Carol (1887) and Rebecca of Sunnybrook Farm (1903).

Kate Wiggin died at Harrow, Middlesex, England.