Eobar Garrington held the mantle of Black Knight during King Richard's Crusades. Following the machinations of the Enchantress centuries later, Garrington's ancestor Dane Whitman was turned to stone and in trying to help him, Doctor Strange sent his conscious into the past where it possessed the body of Eobar Garrington.
Eobar Garrington was created by Steve Englehart and Sal Buscema and first appeared in The Defenders #11.
Major Story Arcs
Fall of Avalon
With the help of Doctor Druid, the Avengers travelled back in time themselves and met the Dane Whitman-possessed Garrington. Garrington died when closing a portal to a dark realm and Whitman's consciousness returned to the future where he was himself once more.