Two knights out-of-time, thrust into the present...and two modern day Templar knights of a different type... each impacting the 20th century in various ways.
Jason Blood was the premier protector of the Camelot of Earth-One, wherein his superhuman alter ego of Etrigan struck terror in his foes. However, facing insurmountable forces, Blood retreated from the battle to protect his home and lived for centuries until the modern era when he was revived in Gotham City, a noted historian who protected to innocent alongside Batman, Wonder Woman, and Superman... among others.
Sir Justin Arthur was the premier protector of the Camelot of Earth-Two, hand picked by his counselor to be the Shining Knight. Given an indestructible golden armor, a sword that could slice through anything, and a flying horse named Winged Victory, Justin had adventures in this historical time period. Then, a battle with a giant ogre sent Justin into the cold waters enveloping him in ice and freezing him for over a thousand years, awakening in a modern era of the 20th century to become one of Law's Legionnaires.
His counterpart of Earth-Two was a criminal gang leader known as the Black Templar, leading forces of the same name. Twice his forces struck against Keystone City, drawing first his henchmen and then himself into conflict with its costumed protector, the Flash. Despite having ancient weaponry, like Grayle originally had in his virtual world, Templar incorporated modern sensibilities into his schemes and nearly succeeded in conquering his city and its prize jewel, Keystone Research which was that world's version of S.T.A.R Labs with cutting edge technology itself, owned by the Flash.