The ruby-crowned kinglet (Corthylio calendula) is a very small passerine bird found throughout North America.

The ruby-crowned kinglet's vocalizations are remarkably loud and complex for its size. Its song can be divided into three main parts: a series of high pitched notes (zee-zee-zee or tee-tee-tee), two to five low trills (turr or tu), and a repeated three note "galloping" phrase (tee-da-leet, tee-da-leet).