Levi Ziegler Leiter (November 2, 1834 – June 9, 1904) was an American businessman based in Chicago. He co-founded what later became the Marshall Field & Company retail empire.^[1][2]

Leiter was born to Anne (née Ziegler) and Joseph Thomas Leiter,^[3] of Leitersburg, the Washington County, Maryland town founded by his granduncle Andrew Leiter.^[4] Although some have confused Leiter's ancestry as Jewish, his family were probably of Swiss-German or Dutch descent. He was raised a Lutheran.^{[3][5][6][7][8]}

As a boy, Leiter worked for a dry goods business in Springfield, Ohio. In 1853 he began working as a bookkeeper at Chicago's then-largest dry goods company, Cooley, Wadsworth & Co., where he worked alongside Marshall Field and Potter Palmer. Leiter and Field became partners in the firm, but in 1865, they sold their interest in the company to John V. Farwell^[9] and went into business, along with Palmer, as Field, Palmer, Leiter & Co.

In 1867, Palmer left his business to pursue real estate ventures, and the company was renamed Field, Leiter & Co. Field & Leiter built a six-story store on State Street in 1868. It was rebuilt after the Great Chicago Fire in 1871. From 1874 to 1880, Leiter was a member of the Executive Committee of the Chicago Relief and Aid Society, which helped collect and distribute funds to rebuild Chicago after the fire. When Leiter sold his interest to Field and retired from the dry goods business in 1881, the name was changed to Marshall Field and Company.

As Leiter's wealth increased, he invested much of his savings in Chicago real estate. After retirement from Field, Leiter & Co., he devoted his attention to real estate and corporate interests.^[10] He later devoted time to travel and philanthropy. He was the first president of the Commercial Club of Chicago, the second president of the Chicago Art Institute, a president of the Chicago Historical Society, and a prominent figure in the Illinois Trust Company.

In 1866, Leiter married Mary Theresa Carver (1844–1913) of Chicago. From 1885 until her death, she served as the second Vice Regent for Illinois in the Mount Vernon Ladies' Association, which is occupied with the preservation of George Washington's Mount Vernon estate. Together, they were the parents of:^[13]

• Joseph Leiter (1868–1932), who married Juliette Williams (1887–1942).^[14]
• Mary Victoria Leiter (1870–1906), who married the British Conservative statesman George Nathaniel Curzon, Viceroy of India, later the 1st Baron Curzon of Kedleston and ultimately 1st Marquess Curzon of Kedleston; she was thus Vicereine of India between 1899 and 1905.^[15]
• Nancy Lathrop Carver Leiter (1873–1930), who married Colin Powys Campbell (1859–1923).^[16]
• Margaret Hyde Leiter (1880–1968), who married Henry Molineux Howard (1877–1917), the 19th Earl of Suffolk and 12th Earl of Berkshire.^[17]

Leiter died of heart disease at the Vanderbilt family cottage in Bar Harbor, Maine on June 9, 1904.^[18] His estate became the subject of eight years of litigation.