VERITAS is an array of four 12-m diameter imaging atmospheric-Cherenkov telescopes located in southern Arizona. Its aim is to study the very high energy (VHE: E>100 GeV) gamma-ray emission from astrophysical objects. VERITAS is currently one of the World's most sensitive VHE gamma-ray detectors and is committed to the intensive study of a wide-varietry of extragalactic sources and related physics. An important contribution to the study of Active Galactic Nuclei (AGN) is provided by coordinated MWL observational campaigns on radio galaxies.
The successful VERITAS research program on the radio galaxy M 87 has provided insights to the jet inner structures and to the emission mechanism in AGN jets. VERITAS discovered also the first extragalactic non-AGN TeV source, the starburst galaxy M 82. Joint VERITAS and Fermi-LAT observations of M 82 provide important clues on possible mechanisms for accelerating cosmic rays. Finally, VERITAS set limits on the number density of primordial black holes from hypothetical gravitational collapse of matter-energy density fluctuations in the early Universe. The VERITAS extragalactic research program and its related results are presented.