Pyrrole is a heterocyclic, organic compound the molecules of which contain a ring of four carbon atoms and one nitrogen. Its chemical formula is C₄H₅N. Pyrrole is colorless liquid that smells like chloroform. Many natural coloring materials are derived from pyrrole, including chlorophyll and hemoglobin.

Ball-and-stick model of a pyrrole molecule. Black = carbon, blue = nitrogen, white = hydrogen