Which singer did Marilyn Monroe help to become the first black woman perform at a famous club?

The singer that Marilyn Monroe helped to become the first black woman to perform at the famous Copacabana nightclub in New York City was Josephine Baker.

This happened in 1951, and while Marilyn Monroe wasn't the sole reason, she did use her influence to get Baker booked. The club had a history of refusing to hire black performers, but Monroe's popularity and the public attention her support brought helped to break down that barrier.