Definition of "oppressor"

And in respect of the great necessity there is, my darling, for more employments being within the reach of Woman than our civilisation has as yet assigned to her, don’t fly at the unfortunate men, even those men who are at first sight in your way, as if they were the natural oppressors of your sex […]

1859, Charles Dickens, The Haunted House

All members of society are hurt by the dynamic of oppressor versus oppressed (McIntosh, 1988).

2006, Lisa V. Blitz, Mary Pender Greene, Racism and Racial Identity