Holly is a tall, pretty Caucasian female, with black hair and blue eyes. She wears a green, long-sleeved dress. She also wears a pair of black, knee-high boots.
At first she seemed nice, but when the gang discovered that she was the true Mastermind, her true colors are revealed to be cruel and vicious, as she tried to frame her uncle to get sent to the jail and make a fortune on his invention.
Scooby-Doo! Night of 100 Frights
Holly lived in Mystic Manor with her uncle, Alexander Graham. She was presumably good friends with Daphne, as Holly recalled that Daphne had kept her up to date on all of the Gang's previous mysteries. She invited the Gang to Mystic Manor because her uncle had gone missing without a trace, right before he was supposed to unveil a new, top-secret invention.
She followed the gang around under the guise of helping them, when in reality she is only there to remove suspicion of her. Sometimes it was not even Holly that was with the gang, but a hologram of her. This would suggest that she had been helping her uncle with his inventions, prior the gang coming, so that she was able to work the machines with ease once the gang arrived.
- At the end of the game, Shaggy Rogers joked that her name, "Holly Graham", obviously sounded like hologram, which is what all the enemies were.
- Despite his own niece trying to set him up, Prof. Graham seemingly forgives Holly.