Ivan Mueller (also spelt Iwan Müller) was a Russian-born clarinetist and inventor who at the beginning of the 19th century was responsible for a major step forward in the development of the clarinet, the air-tight pad.

Mueller was born in Russia. He became a chamber musician in St Petersburg before he was twenty. At the same time, he was constantly striving to improve the clarinet, with new types of keywork. At the time, the standard clarinet used flat brass plates covered in felt to cover the toneholes. Since these leaked air, the number of them had to be kept to a minimum, which meant that notes outside of the main scale of the clarinet (accidentals) had to be got by complicated fingerings which were difficult to play quickly and rarely were in tune.

Mueller went on to work in Dresden, Berlin and Leipzig, where he specialised in the basset horn, a type of low-pitched clarinet.

In 1809, Mueller performed to great acclaim on a clarinet made to his own specifications. On the basis of this performance, the composer Philip Riotti wrote a concerto dedicated to Mueller. Mueller moved to Paris, got a wealthy patron in the form of M. Petit, and started mass producing clarinets.

In 1812, Mueller presented his new 13-key clarinet with air-tight pads to the Paris Conservatoire, but they weren't impressed. Nevertheless, Mueller's new clarinet with fully chromatic range became popular and became the standard clarinet for most of the 19th century.