Eyeless

The Eyeless were an alien species from an unknown planet. They appeared as if they were made out of glass and when some were killed they shattered. They needed to take human eyes to be able to see. One of the Eyeless stole some green eyes from a young girl. The Eyeless arrived at the Fortress to use the weapon at its heart. However The Fortress turned out to be alive and it fought off the Eyeless killing hundreds of them. In the end the Eyeless were able to activate the weapon but it was a dud like it was the first time. (NSA: The Eyeless)