Professor Alexander Graham is an inventor, with a laboratory in Mystic Manor.
Alexander has gray hair and black eyes, and wears round glasses too. He only has hair on the back of his head, but sports a large, grey mustache. He wears a white shirt, with a blue tie, underneath a white lab coat.
Even though he is seen as a great inventor, some of his inventions are items which have already been invented, such as an umbrella, or a set of springs. Other inventions make little sense, including: a solar powered night light, or an underwater tennis racket. When unmasked at the end of the game, he seems unwilling to say that he is not the real Mastermind. This would suggest that he is either very forgiving, or not as willing to cause a scene with Holly. He does not seem fazed by being framed for putting the gang in danger throughout the mystery. His reaction is simply: "Me? Oh, My", which gives the idea that he is very laid-back, or maybe not completely sane.
Scooby-Doo! Night of 100 Frights
He was framed as the Mastermind by his niece, Holly Graham, but her plan was foiled by the gang. It was claimed that he disappeared without a trace, and Mystery Inc. were needed to help find him. It was true that he disappeared, but it turns out Holly knew where he was the whole time, and even used him as part of her plan.
He planned to unveil his new, top-secret invention before his disappearance. However, his inventions seemed to range from useless to bizarre. He left crates all around his own manor before the gang arrived, complete with a video introducing the item and its uses.
- His name, physical appearance and job as a scientist may be a reference to British-Dutchman engineer Alexander Graham Bell, the inventor of telephone.