The Second Lady of the United States or Second Gentleman of the United States (SLOTUS or SGOTUS), is the informal title held by hostess of the Number One Observatory Circle, usually the wife or husband of the Vice President of the United States, during the vice president's term in office. Doug Emhoff is the current Second Gentleman of the United States, in role since January 2021 as the husband of Vice President Kamala Harris.

12 second ladies went on and became become First Lady of the United States following their husbands becoming President of the United States, the first being Abigail Adams and the most recent woman is Jill Biden.