Kryptolian

From Tardis Wiki, the free Doctor Who reference

The Kryptolians were an advanced, warlike species.

They built billions of huge robots known as Sto-cats, and placed them on uninhabited planets, intending to to awaken them a million Brelian years later to subjugate whatever sentient life may have evolved on the planet in the meantime, allowing the Kryptolians to plunder and enslave them. (PROSE: The Sleeping Beast)