The Dark Rider
The Dark Rider was a painting of a highwayman at the International Gallery. It was painted by William Bonneville in 1802. It was animated by Mona Lisa and helped her capture Clyde Langer. Being an animated painting, it could fire a practically infinite number of shots from its flintlock pistols, which are normally only capable of firing one shot each. While it guarded him, Clyde remarked the painting could not talk as it has no visible mouth, for which it was ready to shoot him. The others arrived before it did.
It was returned to its frame when The Abomination was destroyed, breaking the mental link that had animated it. (TV: Mona Lisa's Revenge)