Half the cast of Robin Hood has put in an appearance, including Robin Hood ("The Secret of Chimneys"), Guy of Gisborne ("Ordeal By Innocence"), The Sheriff of Nottingham ("The Moving Finger") Pitts and Matilda ("By the Pricking of My Thumbs").
Likewise, the cast of Merlin also like to visit, and so far has included Morgause ("The Moving Finger"), Edwin Muirden ("Ordeal By Innocence"), Valiant ("Nemesis"), Nimueh and the Witchfinder ("By the Pricking of My Thumbs"), the Gleeman and Lady Catrina ("Sleeping Murder") and Lady Vivian ("Why Didn't They Ask Evans?").
The cast of Sherlock also enjoy making appearances. The the man himself in Murder is Easy, alongside Henry Knight, Mrs. Hudson in Sleeping Murder, Inspector Lestrade in A Pocket Full of Rye, Mycroft in Murder at the Vicarage and Sarah in The Sittaford Mystery