Mauser is most well known from two of it's designs, the Mauser 98 Rifle, and the C96 Broomhandle Pistol.
Mauser created the bolt action system as we know it today, derived from early needle operated systems. Mauser desinged rifles became the standard in most developed European nations by the late 1870's (especially in Germany) The Mauser 98, created in 1898 was, and still is considered one of the best bolt-action rifles ever. The Mauser also featured a five round internal magazine. In a conclusion from the Spanish-American war where the Mauser was being used against us, the United States also switched to using a rifle that highly copied Mauser, the Springfield m1903 The Mauser 98 and variants served Germany through two World Wars, and many third world countries continued using the 98 until the 1980's. Even today many of the most popular bolt-action rifles still use the original Mauser action.
Also, Mauser is generally credited with producing the first practical semi-automatic pistol in 1896, the C96 Broomhandle Mauser which predated the original Luger design by 2 years . Though the borchardt pistol predated it, it was too clumsy for practical use. The C96 served informally in large numbers throughout Europe throughout the World War I Europe, but by far the largest users were the Chinese which used it in large numbers beyond World War II and in many chamberings. A modified C96 was also used as the blaster pistol in the Star Wars original trilogy.
A Broomhandle Mauser pistol.