The vibraphone (also called the vibraharp) is a percussion instrument in the metallophone family. It consists of tuned metal bars and is typically played by using mallets to strike the bars. A person who plays the vibraphone is called a vibraphonist, vibraharpist, or vibist.

The vibraphone resembles the steel marimba, which it superseded. One of the main differences between the vibraphone and other keyboard percussion instruments is that each bar suspends over a resonator tube containing a flat metal disc. These discs are attached together by a common axle and spin when the motor is turned on. This causes the instrument to produce its namesake tremolo or vibrato effect. The vibraphone also has a sustain pedal similar to a piano. When the pedal is up, the bars produce a muted sound; when the pedal is down, the bars sustain for several seconds or until again muted with the pedal.

The vibraphone is commonly used in jazz music, in which it often plays a featured role, and was a defining element of the sound of mid-20th-century "Tiki lounge" exotica, as popularized by Arthur Lyman. It is the second most popular solo keyboard percussion instrument in classical music, after the marimba, and is part of the standard college-level percussion performance education. It is a standard instrument in the modern percussion section for orchestras, concert bands, and in the marching arts (typically as part of the front ensemble).

Around 1916, instrument maker Herman Winterhoff of the Leedy Manufacturing Company began experimenting with vox humana effects on a three-octave (F₃ to F₆) steel marimba. His original design attempted to produce this effect by raising and lowering the resonators, which caused a noticeable vibrato. In 1921, Winterhoff perfected the design by instead attaching a motor that rotated small discs underneath the bars to achieve the same effect. After sales manager George H. Way termed this instrument the "vibraphone", it was marketed by Leedy starting in 1924. The Leedy vibraphone managed to achieve a decent degree of popularity after it was used in the novelty recordings of "Aloha ʻOe" and "Gypsy Love Song" in 1924 by vaudeville performer Louis Frank Chiha.

However, this instrument differed significantly from the instrument now called the "vibraphone". The Leedy vibraphone did not have a pedal mechanism, and it had bars made of steel rather than aluminum. The growing popularity of Leedy's instrument led competitor J. C. Deagan, Inc., the inventor of the original steel marimba on which Leedy's design was based, to ask its chief tuner, Henry Schluter, to develop a similar instrument in 1927. Instead of just copying the Leedy design, Schluter introduced several significant improvements. He made the bars from aluminum instead of steel for a mellower tone, adjusted the dimensions and tuning of the bars to eliminate the dissonant harmonics present in the Leedy design, and introduced a foot-controlled damper bar. Schluter's design became more popular than the Leedy design and has become the template for all instruments now called a "vibraphone".

Both the terms "vibraphone" and "vibraharp" were trademarked by Leedy and Deagan, respectively. Other manufacturers were forced to use the generic name "vibes" or devise new trade names such as "vibraceleste" for their instruments incorporating the newer design.

While the initial purpose of the vibraphone was as a novelty instrument for vaudeville orchestras, that use was quickly overwhelmed in the 1930s by its development in jazz music. The use of the vibraphone in jazz was popularized by Lionel Hampton, a jazz drummer from California. At one recording session with bandleader Louis Armstrong, Hampton was asked to play a vibraphone that had been left behind in the studio. This resulted in the recording of the song "Memories of You" in 1930, containing what is often considered to be the first instance of an improvised vibraphone solo.

In its early history, the vibraphone was often used in classical music to give compositions a jazz influence. The first known composer to use the vibraphone was Havergal Brian in his 1917 opera, The Tigers, which called for two of them. However, since the piece was lost and did not premiere until 1983, Ferde Grofé's Grand Canyon Suite, completed in 1931, is sometimes considered to be the first piece to use a vibraphone instead. Other early classical composers to use the vibraphone were Alban Berg, who used it prominently in his opera Lulu in 1935, and William Grant Still, who used it in his Afro-American Symphony that same year. While the vibraphone has not been used quite as extensively in the realm of classical music as it has with jazz, it can often be heard in theatre or film music, such as in Leonard Bernstein's West Side Story.