The Amadeus Syndicate is an evil corporation and terrorist organization serving as the main antagonists of Metal Slug 4. With the money they were able to obtain from their banks around the world, they became a very rich company. They are allied with the Rebel Army and assisted them when they lost their funding (after the events of Metal Slug 7/XX) by supplying the Rebel Army with more troops, weapons, and vehicles.
Their infantry have the same base sprite as ordinary Rebel Soldiers. They also have blue suited that are better equipped than their green counterparts, suggesting they are some kind of Special Forces unit or honor guards.
- Amadeus is a theophoric given name derived from the Latin words ama – the imperative of the word amare ('to love') – and deus (god). As a linguistic compound in the form of a phereoikos, it means "Love God!". The German-language equivalent is "Gottlieb'; Slavic versions include "Bogumil" and "Bohumil". Other related names are the female form, "Amadea", the French "Amédée (fr)" (male), the Spanish "Amadeo", the Italian "Amedeo", and "Amadis". In contrast, the Greek name "Theophilos" means "friend of God".