Isabel Haslup Lamb (1864–1936) was an American physician and co-founder of the Women's Medical Society of the District of Columbia, with Mary Almera Parsons.

[1] Lamb and her husband Daniel S. Lamb worked for over 30 years at the Woman's Clinic in Washington, D.C., serving on the board and staff alongside Ida Heiberger, Jeannette J. Sumner, and Annie E. Rice, among other prominent women doctors of the day, with a focus on the health of poor women of color.

[8][4] On July 2, 1899, in Towson, Maryland, she married Daniel Smith Lamb (1843–1929), who had been one of her professors at Howard University Medical Center.

[9] Isabel Lamb died of a heart attack at age 71, and she and her husband are buried together in Arlington National Cemetery.

[10] Her obituary in The Washington Star stated that she was the first woman to drive a "horseless carriage" (automobile) in the District of Columbia, and that her nickname was "Aunt Carester.