Hey, It's That Guy!: A ton of this. A lot of British stage actors are in this series, many of them from well-known shows and films. Here's a rundown:
: Richard II Bill Tanner, whose father is Captain Jean-Luc Picard, leads a rebellion against Q, who banished him from England following a duel with Mark Antony( who looks a lot like the Black Prince). He is assisted in this endeavor by Jackson Lake and Hercule Poirot. Meanwhile, Queen Fleur Delacour grieves for her husband after learning the news from Walder Frey.
: Henry IV Scar is King of England, but is concerned that his son and heir, Loki, is a wastrel who spends all his time in a rundown pub owned by Molly Weasley palling around with Fred Best. Meanwhile, Allan A Dale, who is married to Mary Crawley and the son of Thenardier, is leading a rebellion against the throne, alongside Viserys Targaryen, who is the son-in-law of Craster. Jorah Mormont also shows up as a nobleman in the English court.
: Henry V Loki leads the English army to victory at Agincourt. Uncle Vernon shows up as the Duke of Burgundy, and Ser Aliser Thorne is a Welsh captain in the English army. The Elephant Man lives to tell the tale.