Bark is the canine companion of an ancient Waldini ancestor featured the in Where's Waldo? episode "A Stone Age Story". The prehistoric dog wore red and white stripes, a bobble hat, and glasses. Bark follows the prehistoric member of the Waldini clan on his travels and (just like Woof) is often found rolling his eyes at the nerdiness and optimism of his adventuresome master.
Similar to the name "Woof", the name of "Bark" came from a common onomatopoeia for the sound a dog makes.