Hell, Monster Motorbike

If a two-wheeled vehicle with steam propulsion is considered a motorcycle, then the first was the French Michaux-Perreaux steam bicycle of 1868. This was followed by the American Roper steam velocipede of 1869, built by Sylvester Howard Roper of Roxbury, Massachusetts. Roper demonstrated his machine at fairs and circuses in the eastern U.S. in 1867, and built a total of 10 examples.
In 1894, Hildebrand & Wolfmüller became the first series production motorcycle, and the first to be called a motorcycle (German: Motorrad). In the early period of motorcycle history, many producers of bicycles adapted their designs to accommodate the new internal combustion engine. As the engines became more powerful and designs outgrew the bicycle origins, the number of motorcycle producers increased.
Until World War I, the largest motorcycle manufacturer in the world was Indian, producing over 20,000 bikes per year. By 1920, this honour went to Harley-Davidson, with their motorcycles being sold by dealers in 67 countries. By the late 1920s or early 1930s, DKW took over as the largest manufacturer.
After World War II, the BSA Group became the largest producer of motorcycles in the world, producing up to 75,000 bikes per year in the 1950s. The German company NSU held the position of largest manufacturer from 1955 until the 1970s.