Martin Leopold Widhalm (October 2, 1722 – June 10, 1776) was an Austrianluthier.
Born in Horn, Austria, he worked on many old Bologna lutes that inspired his later work in his manufacture of lutes, violins and violoncellos in Nuremberg, Germany between 1746 and 1776. Widhalm moved permanently to Nuremberg in 1745 to work at the instrument making shop of the late Sebastian Schelle (1676–1744) being run by his eldest daughter Barbara. The couple's working relationship became personal and resulted in marriage the following year. However, a prolonged legal battle ensued with Leonhard Maussiell (1685–1760), who objected to Widhalm taking over the business.
When legal matters finally ended, Leopold and Barbara Widhalm created the largest and most successful lute and violin manufacturing operation in Nuremberg, noted for their outstanding quality. Following his death in 1776 and her death in 1781, their sons Martin Leopold Widhalm (1747–1806) and Gallus Ignatius Widhalm (1752–1822) took over from him and a grandson, Johann Martin Leopold Widhalm (1799–1855) too became involved in the business.