Walter Ashby Plecker (April 2, 1861 – August 2, 1947) was an American physician and public health advocate who was the first registrar of Virginia's Bureau of Vital Statistics, serving from 1912 to 1946.

A eugenicist and proponent of scientific racism, Plecker drafted and lobbied for the passage of the Racial Integrity Act of 1924 by the Virginia legislature; it institutionalized the one-drop rule.

[2] He was a devout Presbyterian, and throughout his life, he supported the denomination's fundamentalist Southern branch, funding missionaries who believed, as he later would, that God had destroyed Sodom and Gomorrah as punishment for racial intermixing.

[3] Plecker settled in Hampton, Virginia, in 1892, and before his mother's death in 1915, he worked with women of all races and became known for his active interest in obstetrics and public health issues.

[5] He wanted to prevent miscegenation, or marriage between races, and he also thought that a decreasing number of mulattoes, as classified in the census, meant that more of them were passing as white.

[5][6] With the help of John Powell and Earnest Sevier Cox, Plecker drafted and the state legislature passed the "Racial Integrity Act of 1924".

Plecker refused to recognize the fact that many mixed-race Virginia Indians had maintained their culture and identity as Native Americans over the centuries despite economic assimilation.

Specifically, Plecker ordered state agencies to reclassify certain families whom he identified by surname, because he decided that they were trying to pass and evade segregation.

In 1935, a decade after the passage of Virginia's eugenics laws, he wrote to Walter Gross, director of Nazi Germany's Office for Enlightenment on Population Policy and Racial Welfare.