The Klingon disruptor was an evolving standard for hand-held weapons, disruptor devices used by the Klingons for a number of centuries. Like the phaser, they were a form of particle beam weapon. Larger variants were also mounted on starships. Among other species to use the disruptor were the Romulan and Breen species.
During the Broken Bow Incident of the year 2151, Klingon courier Klaang used his disruptor in Broken Bow, Oklahoma. There, he was able to use the disruptor to kill a pair of Suliban Cabal soldiers. (ENT episode & novelization: Broken Bow)
In the Federation-Klingon Cold War of the 23rd century, disruptors were the standard sidearm of Klingon troops and officers, being frequently encountered by the crew of the USS Enterprise. (TOS episode & novelization: Errand of Mercy)