The clarinet is a musical instrument in the woodwind family. The name derives from adding the suffix -et (meaning little) to the Italian word clarino (meaning a type of trumpet), as the first clarinets had a strident tone similar to that of a trumpet. The instrument has an approximately cylindrical bore, and uses a single reed.

Clarinets comprise a family of instruments of differing sizes and pitches. The clarinet family is the largest such woodwind family, with more than a dozen types, ranging from the BB♭ contrabass to the E♭ soprano. Of these many are rare or obsolete, and music written for them is usually played on one of the more common types. The unmodified word clarinet usually refers to the B♭ soprano clarinet, by far the most common clarinet.

A person who plays the clarinet is called a clarinetist or clarinettist. The clarinet was invented in Germany by Johann Christoph Denner around the turn of the 18th century, by adding a register key to the earlier chalumeau. Over time, additional keywork and airtight pads were added to improve tone and playability. Today, the clarinet is used in both jazz and classical ensembles, as well as in chamber groups and as a solo instrument.