Ellie Kemper

Kemper was born in Kansas City, Missouri, the second of four children of Dorothy Ann "Dotty" (née Jannarone) and David Woods Kemper, a son of one of the wealthiest families in Missouri. Her father is the executive chairman of Commerce Bancshares, a bank holding company founded by the Kemper family. She is the granddaughter of Mildred Lane Kemper, namesake of the Mildred Lane Kemper Art Museum at Washington University in St. Louis and the great-great-granddaughter of banker William Thornton Kemper Sr.

She is the elder sister of television writer Carrie Kemper. Kemper is of Italian (from her maternal grandfather), English, French, and German ancestry. She was raised and remains a practicing Roman Catholic.

In 1999, at age 19, she was presented as a debutante at the Veiled Prophet Ball, and was named the Veiled Prophet's Queen of Love and Beauty. Her participation sparked controversy in 2021 due to the Ball's background, which was described as "racist and elitist". The backlash prompted Kemper to release a statement denouncing white supremacy and apologizing for participating in the event.