Cathal Joseph "Carl" Smyth, also known as Chas Smash, is an English singer-songwriter and multi-instrumentalist. He was the secondary vocalist, trumpet player and dancer for the English band Madness from their inception in the late 1970s until 2014.

Madness are an English ska and pop band from Camden Town, north London, who formed in 1976. One of the most prominent bands of the late 1970s and early 1980s two-tone ska revival, they continue to perform with six of the seven members of their original line-up. Madness's most successful period was from 1980 to 1986, when the band's songs spent a total of 214 weeks on the UK Singles Chart.