The Omega is the main antagonist in the 2013 science-fantasy movie Edge of Tomorrow.
In the near future, a meteorite crashes near Hamburg. Hordes of extremely organized aliens, the Mimics, invade Europe, led by Omega. A coalition of seventeen nations is formed to fight mimics. It is called the United Defense Force (UDF). In five years, this world war claimed millions of victims. The mimics seem to anticipate all the actions of the military. But suddenly, the humans win the Battle of Verdun with very low losses. This victory is the work of Sergeant Rita Vrataski who killed hundreds of mimics on her first day of combat, equipped with the new armor. She thus became the heroine of the army and the media nicknamed her "the angel of Verdun".
Major William Cage, the protagonist of the story, acquired this ability after killing an Alpha Mimic, though he didn't realize it at the time. They team up together and decide to use this ability to destroy the Omega. His location appears to Cage as a vision.
It takes him many attempts to reach the place where the Omega is hiding (the Curnera dam in Switzerland), but he realizes on the spot that it is a trap, and that the Omega is finally not there. Cage and Rita then change tactics, and decide to use a transponder that would allow Cage to locate the Omega. However, this device is owned by General Brigham. They then try, on multiple occasions, to reach the general without being detected, in order to convince him to give them the necessary part, and finally manage to escape with it. The day Cage manages to use the transponder, he discovers that the Omega is ambushed in the flooded undergrounds of the Louvre museum in Paris.
Going down into the underground parking lot where the Omega is, the two survivors spot an Alpha. Rita decides to sacrifice herself by creating a diversion in order to allow Cage to go to the Omega and destroy it. Rita tells Cage that she wished she had the chance to get to know him a bit more. She kisses him then leaves for the Alpha. Cage dives and swims towards the Omega. As he prepares to take his explosives sling, the Alpha pierces him with a tentacle. Cage drops the explosives into the Omega before dying, causing all of the aliens in the explosion to be annihilated, Omega included.
The Omega is the being that sent the Mimics to Earth, and therefore, it is responsible for the events of the film. Since it is the hive mind for the Mimics, they are telepathically connected to it; for that reason, if it is destroyed, the Mimics cease to function. It also has the ability to reset the day of the battle where the film takes place so that the Mimics can learn and adapt to battle strategies.
His motives and personality are little known. However, Omega is very intelligent and strategic, being able to set Cage and Vrataski into a trap by sending them a vision indicating a false location.