The Dog Star is a nickname for Sirius, a star in the constellation Canis Major (Greater Dog).
Dog Star or Dogstar may also refer to:
- Dogstar (band), a rock group including Keanu Reeves
- "Dog Star" (short story), a short story by Arthur C. Clarke
- Dogstar (TV series), a 2006 animated Australian TV series
- "Dogstar", a song by Hybrid from the 2006 album I Choose Noise
- "Dog Star", a song by Klaatu from the 1980 album Endangered Species
- The Dog Star, a 1950 novel by Donald Windham
- The Dog Stars, a 2012 novel by Peter Heller