William Ernest Metzger (September 30, 1868 – April 11, 1933) was an automotive pioneer and salesman from Detroit. He opened one of the first automobile dealerships in the United States, and participated in the early development of a number of early automobile companies, including the Cadillac Automobile Company and the E-M-F Company, in which the "M" stands for his name.

William Metzger was born in Peru, IL, in 1868.[1] At the age of 10 he moved to Detroit with his father; he graduated from Detroit High School in 1885. He immediately got a job at Hudson & Symington furniture (owned by J. L. Hudson).[2] As a young man, Metzger became enamored of bicycle riding, becoming the first vice president of Detroit's Wheelman's Club and finishing a number of 100-mile bicycle rides. Soon his hobby became his business: in 1891, Metzger joined Stanley B Huber to open Huber & Metzger, a bicycle shop located in the center of downtown Detroit. The store soon became one of the largest in the country, and dealt directly with suppliers in England.

In 1895, Metzger attended the world's first automobile show in London. Impressed with what he saw, he went on to visit the factories of Gottlieb Daimler and Karl Benz, then the leading automobile manufacturers in the world (albeit with less than 200 each). He returned to Detroit convinced of the automobile's future, and immediately sold his share in Huber & Metzger. Metzger built the first U. S. automobile retail showroom, which opened in 1897, selling Waverley electric cars. The following year, Metzger added steamers, then gasoline-powered cars built by various companies. In 1899, Metzger started selling automobiles built by Oldsmobile; in June, Metzger sold the first automobile built by the company. In 1899, Metzger helped organize the Detroit Auto Show, only the second of its kind. The next year, he helped stage the New York Auto Show in New York's Madison Square Garden. He also promoted racing, putting up the $200 prize won by Barney Oldfield driving the Ford 999 -- a win that had a substantial impact on Henry Ford's fortunes. In 1900, he organized the Northern Motor Car Co. Two years later, Metzger was one of the people who organized the Cadillac Motor Car Co. In 1903, with only three cars produced, Metzger took orders for 2700 cars at the New York Auto Show. The 1903 production of Cadillacs outstripped every other manufacture in the US save Oldsmobile. In 1905, Cadillac reorganized, merging with Leland & Faulconer; Metzger obtained 3000 shares of the merged company. Metzger stayed at Cadillac as sales manager until 1908, but was looking for new challenges.