Zeta Ori (ζ Ori), traditionally known as Alnitak, is a triple star some 800 light years distant in the constellation Orion. Together with Delta Orionis (Mintaka) and Epsilon Orionis (Alnilam), the three stars make up the belt of Orion, known by many names across many ancient cultures. Zeta Orionis (ζ Ori) is the left-most star.
The primary star is a hot blue supergiant with an absolute magnitude of -5.25, and is the brightest class O star in the night sky with a visual magnitude of 1.70. It has two bluish 4th magnitude companions. The stars are members of The Orion OB1 Association.