Omega is central commander of all Mimics appearing in Edge of Tomorrow.
Overview
The Omega is the central intelligence of the Mimics. It is a massive, hive-like organism that conceals a glowing brain-like core. An Omega is linked to all Mimics, and possesses the ability to turn back time in order to continuously retry different battle strategies until the Mimics win. This ability has been used countless times by the Omega to allow the Mimics to lay siege to nearly all of Central Europe. It's highly intelligent and can quickly come up with different combat tactics. It can also trackdown and send manipulative visions to people infected with an Alpha's blood.
The Omega doesn't possess any abilities to defend itself from a threat. Instead it keeps itself hidden and relies on Alphas and Drones to protect it from danger.
Design
Omega looks like a giant bio-mechanical structure with a giant sphere in the middle and long spikes that can close onto itself sticking out around its sides.