In life he appeared as a old man with a long bushy white beard, tanned skin, and a brownish red pirate uniform with a matching hat and a rapier. He also had a moon shaped scar around his eye. As a zombie he is much thinner to point where he is mostly skin and bones, his clothes are tattered and his rapier is rusty in numerous places.
Nothing is explicitly stated about Morgan's personality, but he certainly seems to be a typical bloodthirsty pirate captain. He murders an entire settlement to ensure they would not get (or talk about) his buried treasure.
Following his demise, he joined the other people that fell victim to Simone, and Jacques, in their efforts to try to warn people of the danger they posed, although whether this was to prevent other people from suffering his fate or simply to get revenge on Simone for killing him is unclear.
Sometime in the 1700s, Morgan Moonscar and his crew of pirates arrived on an island now known as Moonscar Island. While the residents were having a party, celebrating their cat goddess, Morgan Moonscar and his crew attacked them. He forced the residents into the bayou, resulting in them getting eaten by alligators. However, two of the residents, Simone Lenoir and Lena Dupree managed to escape from Moonscar and the pirates. In utter rage and hatred, the two women uttered a curse on the pirates, which resulted in them becoming werecats. With their new powers, the two killed Morgan Moonscar and the pirates. They would only be their first victims.
Scooby-Doo On Zombie Island
Moonscar, along with his crew and the other victims were left to wander Moonscar Island after having the life drained from them. 200 years later, they tried to drive Mystery Inc. off the island. After Simone died, the souls of Moonscar and his crew were released, along with those of the other zombies, allowing them to finally rest in peace in the afterlife.