Prakseda Marcelina Kochańska (February 15, 1858 – January 11, 1935), known professionally as Marcella Sembrich, was a Polish dramatic coloratura soprano. She is known for her extensive range of two and a half octaves, precise intonation, charm, portamento, vocal fluidity, and impressive coloratura. Her voice was regarded as flute-like and pure. She had an international singing career, chiefly at the New York Metropolitan Opera and the Royal Opera House, in London.