The Singing Cactus are mysterious plant-like creatures that live near Wonder Mountain.

They resemble the Sirens from Greek mythology, as their mysterious doo-wop hit song "Do the Sashay" has the powers to brainwash whoever hears it. Red Fraggle becomes the first explorer to discover them and accidentally makes the leader begin the song as she tries to measure them off to prevent Mokey Fraggle from going near them. Mokey saves Red from her fate by wearing radishes in her ears as earplugs, leaving a few disappointed cacti behind.

They appear again as Red and Mokey lure The Avalanche Monster to them in order for the two to continue their journey to Wonder Mountain.