A VALIANT EFFORT

In the second episode of 'Merlin', the villain was a knight named "Valiant". Could it be that he was supposed to be a tele-version of the classic comic strip character Prince Valiant?

Prince Valiant does have a strong presence in the Tooniverse, as well as in the universe for movies (where he was played by Robert Wagner).
Save for the name, nothing about Will Mellor would suggest the Hal Foster character. But then again, nothing about this series is anything like the established views of Merlin and the man who would be king, Arthur.
And it is at least once removed from the main Toobworld, Earth Prime-Time, because of that deviation from the legend's norm.

So in the end, it doesn't matter. And therefore, why am I even bothering you with this?

BCnU!