Aldebaran (also known as Alpha Tauri) is a binary star system located about 65.1 light years from Sol. Aldebaran is the brightest star in the constellation Taurus and one of the brightest stars in the nighttime sky. Because of its location in the head of Taurus, it has historically been called the Bull's Eye. Aldebaran has the appearance of being the brightest member of the more scattered Hyades cluster, which is the closest star cluster to Earth. However, it is merely located in the line of sight between the Earth and the Hyades, and is actually an independent star. NASA's Pioneer 10 spacecraft, which flew by Jupiter in 1973 will reach and pass by Aldebaran in about two million years.

In Star Trek, this system was the location of the Aldebaran colony, the home to the Aldebaran mud leech, the Aldebaran serpent, Aldebaran whiskey, and the Aldebaran shellmouth. (ENT: "Anomaly"; TOS: "Where No Man Has Gone Before", "Amok Time"; TNG: "Hide and Q", "Conspiracy", "Relics"; DS9: "Prophet Motive", "Explorers", "Distant Voices"). The Aldebaran colony was a Federation colony in the Aldebaran star system. Doctor Elizabeth Dehner joined the crew of the USS Enterprise when it stopped at the colony in 2265. She had been posted on Aldebaran to complete her thesis for the College of Medical Sciences of the Tri-Planetary Academy on the subject of participation in testing and study of beings that harness psionic energy. (TOS: "Where No Man Has Gone Before")

In reality, Aldebaran is a K5III star, which means it is orangish, large, and has moved off the main sequence after exhausting the hydrogen fuel in its core. It has a minor companion (a dim M2 dwarf orbiting at several hundred AU). Now primarily fusing helium, the main star has expanded to a diameter of 44.2 times the diameter of the Sun, approximately 61 million kilometres. It shines with 150 times the Sun's luminosity. With an apparent magnitude of 0.87, it is the 13th brightest star.

Aldebaran is one of the easiest stars to find in the night sky, partly due to its brightness and partly due to its spatial relation to one of the more noticeable asterisms in the sky. If one follows the three stars of Orion's belt from left to right (in the Northern Hemisphere) or right to left (in the Southern), the first bright star found by continuing that line is Aldebaran.