Mary Ellen Peters Black (1851–1919) was a prominent organizer and activist related to women's issues in Georgia.

In a letter to the Negro Women's Clubs, Black told the group that "until you teach your people not to molest the whites, there could be no adjustment.

"[3] Black's father, Richard Peters, moved from Pennsylvania to Georgia to survey the railroads, working as a civil engineer.

[2] Her mother, Mary Jane Thompson, was involved in social clubs and outreach in Atlanta, where Nellie grew up.

She soon convinced city officials to build drinking fountains for horses exhausted from the summer heat; it was one of her first examples of civic activism.