Homer "Si" Blankenship (August 4, 1902 – June 22, 1974) was an American pitcher in Major League Baseball with the Chicago White Sox and Pittsburgh Pirates.
Blankenship, a Cherokee Native American, was born in Bonham, Texas, and attended high school in Ada, Oklahoma. He is a year younger than his brother Ted Blankenship, who pitched in the major leagues for 9 seasons. Homer made his MLB debut for the White Sox in 1922, at the age of 20. He played in Chicago for parts of two seasons. Besides a short stint with the Pirates in 1928, he then pitched in the Texas League from 1926 to 1930. He won a career-high 17 games for the Shreveport Sports in 1926.
Blankenship retired from professional baseball in 1931. He died in 1974 in Longview, Texas.