The ghost of Jacob Marley was the disguise of Dr. Buggly, the doctor taking care of Ebenezer Scrooge. Buggly used the disguise to scare Scrooge into changing his miserly ways.
Physical appearance[]
The ghost of Jacob Marley is depicted as having pale blue skin, white hair, bushy eyebrows, green eyes and black sclera. He wore a tattered jacket and pants over a bluish gray vest and white collared shirt along with a blueish-gray bowtie as well as a gray bandage around his head. True to the original A Christmas Carol, he was entwined with handcuffs, chains, and locks connected to money boxes which he dragged.
Personality[]
In A Christmas Carol, Jacob Marley was Ebenezer Scrooge's business partner, who, after his death, was condemned to wander in chains for his life of greed. As such, despite being intimidating, he sought to warn his friend to change his ways to save him from a similar fate.
History[]
Be Cool, Scooby-Doo![]

Dr. Buggly disguising himself as the ghost of Jacob Marley.
Season two[]
In a retelling of Charles Dickens' novel A Christmas Carol, the ghost of Jacob Marley was the disguise of Ebenezer Scrooge's doctor, Dr. Buggly. Buggly wanted to change Scrooge's selfish and miserly ways so he would pay for his clerk's son's medical treatment. The ghost of Jacob Marley would then be followed by the Ghosts of Christmas Past, Present, and Yet to Come, which would each appear to Scrooge and show scenes of his past, present, and future life. However, Mystery Inc. would capture and expose Buggly as the Ghost of Christmas Yet to Come.