Prince Valiant guest-starred here. Like Flash Gordon, The Phantom, and Mandrake the Magician, Prince Valiant is a King Features Syndicate comic-strip character. Dan Gilvezan, who voiced him, would later star in the series The Legend of Prince Valiant (1991) as a few roles beginning with a supporting one, and Peter Renaday (Mandrake) would portray Valiant's father (though his name was changed from King Aquar).
This is the 27th Phantom.