Frederica (Frederikke) Louise Ernst (1714–1781) was a Danish merchant, ship owner and slave trader.
Her maternal grandfather was rector of the Metropolitan School Peder Nielsen Foss (1631-1698).
Being an unmarried woman, she was legally under the guardianship of her closest male relative for life.
She was a successful businesswoman and invested in a number of business: she owned shares of a warehouse, ships and a sugar plantation on Danish St. Croix.
Initially successful, in 1772, she tried to recoup her loans, but her money was tied up in the West Indies.