Dennis is light greenish blue, but is light brown in the episode "The Sponge Who Could Fly." He is in the Mild Ones biker gang, and is also the manager of Barg'N Mart. He normally wears a pair of eyeglasses, a top hat, or purple shorts with orange polka-dots on them.
Dennis went to the same elementary school with SpongeBob.
He is convinced by Mr. Krabs to buy an umbrella in his yard sale in this episode, saying that it is the queen of Switzerland. Dennis then replies that Switzerland has no queen. However, he buys the umbrella anyway.