"Clancy Lowered the Boom" is a song written by Hy Heath & Johnny Lange in 1947, made famous by Dennis Day on Jack Benny's radio program (The Jack Benny Program). The song follows the adventures of an Irish-American stereotype as he "lowers the boom" on any person that gives him "guff".

On his VH1 Storytellers record with Willie Nelson, Johnny Cash mentions that the melody for his well-known Columbia Records hit "Don't Take Your Guns to Town" was taken from "Clancy Lowered the Boom".

It was also recorded by Bing Crosby, and it was Petula Clark's second single in 1949.

Several variations of the lyrics are available online, but do not include the final line from Dennis Day's RCA recording: "Sure, 'twas the most beautiful fight y' ever did see when Clancy lower'd the boom!"