Hey, It's That Guy! - A bizarre variation; because the characters are done with the Half-Life models, you have Barney Calhoun "playing" John Rourke, among others. The most noteworthy is the calm and prudish but nice and otherwise normal Mister Smith played by the G-Man.
The offscreen villains of Clear Skies 3 are a Mega Corp. called Otherworld Enterprises, a mining conglomerate which legally stole the planet out from under the settlers. It sounds like a throwaway line to people not familiar with the game world; those in the know will recognize Otherworld Enterprises as the corporate front of the legendary Chribba, "the only honest man in EVE."