Omega (Ω ω) (literally, big O) is the 24th and last letter of the Greek alphabet. In the Greek numeric system it had a value of 800.

Omega is used to denote an end to something, the opposite being Alpha, beginning. For example, "I am Alpha and Omega, the beginning and the end, the first and the last." (Revelation 22:13, KJV)

Omega has been used as the name for a wide variety of other things, for example:

• Omega is a Swiss watch company.
• Omega is the name of the free 16-Bit (Unicode) version of the typesetting system TeX ([1] (http://omega.enstb.org/))
• Omega is a fictional character from the television program Doctor Who.
• a Roguelike game ([2] (http://www.win.tue.nl/~kroisos/omega/))
• a fatty acid: Omega-3 fatty acid
• the lowest ranking position in a group of animals (the omega (wolf) in a pack)
• a line of Omega and Omegaflex roll film cameras
• Omega was the first worldwide radio navigation system

The upper-case letter Ω is used as a symbol for:

• the best person in a group of people. The Omega person, the leader the most valued and accepted member.
• Ohm - SI unit of electrical resistance.
• In computer science, in notation related to Big O notation, also Chaitin's constant.
• Codex Athous Dionysii, an 8th/9th century uncial Greek manuscript of the Gospels on Mount Athos.
• Omega Point, a theory about computing at the end of the universe.
• In mathematics, the first uncountable ordinal number.
• In mathematics, the Omega constant.
• Naoki Maeda's pseudonym for the Dance Dance Revolution song Max 300.

The lower-case letter ω is used as a symbol for:

• In textual criticism, the archetype of a manuscript tradition.
• In physics, angular velocity.
• In mathematics, the first transfinite ordinal number