"Keep the magic secret."

Keep the magic secret is the tagline for the show Merlin. It is used for publicity and is designed to reflect an aspect of the show's main character, Merlin.

It is based on the fact that Merlin has magic but in Camelot such powers are forbidden so he must keep his gifts a secret. The only people in Camelot who know about his powers are Gaius, Kilgharrah and also Lancelot, a deceased knight of the round table.