Levi Ziegler Leiter (November 2, 1834 – June 9, 1904) was a Chicago businessman. He co-founded what became the Marshall Field & Company retail empire.
Leiter was born to Anne (née Ziegler) and Joseph Thomas Leiter, of Leitersburg, the Washington County, Maryland, town founded by his grandfather, Abraham Leiter. Leiter's family was of German Swiss descent, and some of his ancestors had been Mennonites. Leiter was raised a Lutheran.
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 and went into business, along with Palmer, as Field, Palmer, Leiter & Co.
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.
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. 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.