Ubar may refer to:
- Ab Bar
- A legendary land in southern Arabia, often referred to as Atlantis of the Sands, which is considered by some to be the same as:
- The Wabar or Ubar craters, near the lost Arabian city
- U bar, a letter of the Latin alphabet, thats formed from U with the addition of a bar: Ʉ, ʉ.
- μbar, a unit of pressure