Matthew Colless has led high-impact research in the fields of observational cosmology, galaxy and cluster evolution and the large-scale structure of the Universe, and has driven the development of multi-object spectroscopy in the new field of statistical astronomy. In particular, his conception of, and his leadership of, the 2dFGRS survey has firmly established the values of many key cosmological parameters. These include the determination of the Hubble constant, the cosmological constant, the matter density in the Universe, the baryonic to dark matter fraction, and an upper limit on the neutrino fraction.