1651

In 1651, the Twelfth Doctor tracked the Eyes of Hades to the south of England, where he encountered the immortal human Ashildr - going by the aliases "Lady Me" and "the Knightmare" - following their previous meeting eight hundred years earlier. Ashildr and the Doctor worked together to find the Eyes; Ashildr later revealed that she had struck a deal with Leandro, a native of Delta Leonis - the planet on which the Eyes originated - in an attempt to escape Earth. Her plan backfired when Leandro betrayed her, revealing he was the advance scout for a Leonian invasion.

The Twelfth Doctor and Me in 1651. (TV: The Woman Who Lived)

Using the Eyes of Hades, Leandro opened a rift in space, through which his people planned to invade Earth. However, the Doctor and Ashildr were able to close the portal, and Leandro was remotely executed by his "brothers" for his failure. (TV: The Woman Who Lived)