Parzival

Parzival of the Vegracandis was a small, alien, dog-like creature which attempted to help the King win the English Civil War, hoping to influence the planet from a position of power. He concealed himself on the back of Prince Rupert’s dog, Boye, and emitted a bark that rendered those around temporarily unable to move or speak by freezing their higher brain activity. The Doctor used his sonic screwdriver to make Parzival reveal himself and took him away in the TARDIS. (DWA: Dog of War!)