CMX, originally Cloaca Maxima, are a Finnish rock band. They originally played hardcore punk, but soon expanded to play a wide variety of rock formats, including progressive rock, heavy metal, and mainstream rock 'n' roll. Throughout their career, they have been influenced by progressive rock bands such as Rush, Yes, Tool and King Crimson. The progressive influence is most evident on their albums Dinosaurus Stereophonicus (2000) and Talvikuningas (2007).

CMX have gradually gained large-scale mainstream following in Finland. They are especially known for the poetic lyrics of A. W. Yrjänä that often contain references to mythology and religion. Finnish rock magazines, particularly Rumba, have named them Best Band of the Year multiple times, and even Best Band of All Time on one occasion.