Omega is the last letter in the Greek alphabet. See that article for more uses of the upper case (Ω) or lower case (ω) letter as a symbol.

Omega could also mean:

Alphabet 
 Omega (Cyrillic), the Cyrillic counterpart of Greek omega.

Mathematics 
 Lambert W function, also known as the omega function.
 Omega constant, a specific value derived from Lambert's W function.
 Chaitin's constant, or Halting Probability, written as Ω.

Science 
 Omega loop, a protein motif
 Omega-3 fatty acid
 Omega-6 fatty acid
 Omega-9 fatty acid
 Omega particle, a subatomic particle
 Omega, in sociobiology, the lowest rank in a dominance hierarchy
 In cosmology, the density parameter

Technology 
 Omega (camera), a brand of cameras and enlargers
 OMEGA Navigation System, the first worldwide radio navigation system
 Omega SA, a Swiss watch company
 Omega (TeX), a Unicode extension of the TeX typesetting system
 Omega drivers, third-party drivers for ATI and nVidia graphics cards

Military 
 OMEGA, a Latvian special operations unit

Philosophy 
 Omega point, an idea in philosophy (eschatology) advanced by Pierre Teilhard de Chardin

Places in the United States 
 Omega, Georgia
 Omega, Oklahoma
 Omega D.C., a gay bar in Washington, D.C.

Automobiles 
 Opel Omega, a car model by Opel/Vauxhall
 Oldsmobile Omega, another General Motors car, mechanically unrelated to the above

Fiction 
 Omega (Doctor Who), a fictional character from the television series
 Omega (Doctor Who audio), a Big Finish Productions audio drama based on Doctor Who
 The Omega Directive, an episode of Star Trek: Voyager
 Omega Ranger, a character from Power Rangers: S.P.D.
 The Omega Man, a 1971 science fiction film
 Omega, an alias of O'Malley, a character in Red vs. Blue
 Omegamon and Omegamon X, the Japanese names for the Digimon characters, Omnimon, as well as his X-Antibody counterpart, Omnimon X
 Doctor Omega, a 1906 science fiction novel by Arnould Galopin
 Omega (novel), a science fiction novel by Jack McDevitt
 A character in the Maximum Ride series.
 The Omega Lock in Transformers Cybertron.
 Omega (film), a Greek thriller, directed by Vasilis Blioumis

Comic books 
 Omega Red, a comic book supervillain in the Marvel Comics universe
 Omega-level mutant, the most powerful Marvel Comics mutants
 Omega (comics), a comic book villain from the Legion of Super-Heroes
 Omega Men, a DC Comics superhero group
 Omega the Unknown, a 1970s Marvel Comics series created by Steve Gerber

Video games 
 Omega (1987 computer game), a Roguelike game
 Omega (1989 computer game), a game by Origin Systems
 Omega (Dead or Alive), the final boss of Dead or Alive 3
 Omega (Final Fantasy), a recurring boss in the Final Fantasy series
 E-123 Omega, a character in the Sonic the Hedgehog series
 Omega, one of the main antagonists and the final boss of Mega Man Zero 3
 Omega is the pseudonym used by Naoki Maeda for the song "MAX300" from DDRMAX: Dance Dance Revolution 6thMIX

Music 
 (Omega) y su Mambo Violento, a Dominican musical group
 Omēga and the Mechanical Animals, a fictitious rock band portrayed by Marilyn Manson on their album Mechanical Animals
 Omega (band), a Hungarian rock band
 Omega No. 5, an album by Scaterd Few
 Omega (song), a song by Rebecca St. James
 Deathspell Omega, a French black metal band
 The Omega Rising, an album by Profundi, a Swedish black metal band
 Omega Recording Studios, a recording school and studio located outside of Washington D.C.

Other uses 
 Omega (cider), a strong white cider
 Omega Psi Phi, African American fraternity and member of the National Pan-Hellenic Council
 Organization of Modern Extreme Grappling Arts (OMEGA), a wrestling promotion owned by Matt and Jeff Hardy
 Omega Development Site, planned to be one of Europe's largest business parks, in Warrington, Cheshire