Delta Sigma Theta Sorority is celebrating its Founders Day today. The empowering women's organization was founded on January 13, 1913, by 22 collegiate women at Howard University. Delta Sigma Theta is one of the oldest and largest African American Greek-lettered organizations. [RELATED: Lincoln Motor Company Lends Support to Black Greek Organizations] Check out these 10 celebrity Deltas who have been leaders in their industries: Actress and Activist, Sheryl Lee Ralph: Singer and Reality TV Star, K. Michelle: Actress, Angela Bassett: Singer, Nancy Wilson: Hollywood Producer, Mara Brock Akil: Singer, Shirley Caesar: Actress, Cicely Tyson: Journalist, Gwen Ifill: Religious Leader, Rev. Vashti McKenzie: Neurosurgeon, Dr. Alexa Irene Canady: