Shannon was first seen during the Celebrity Heat News broadcast. She later welcomes Daphne, Velma and the Mystery Inc. boys onto Sly Baron's spaceship and commented on their nice spacesuits and their results on the space test they took, claiming Daphne's score to be the highest, much to Velma's jealousy. Once in space, she used her alien costume to damage the ship, causing it to land on Sly's resort on the dark side of the moon. She then terrorized Scooby-Doo and Shaggy Rogers with her alien costume. Eventually she was caught by one of Fred Jones' traps and unmasked. She then told the gang her evil plan, because she was outraged that she had to work hard to become an astronaut, while everyone else was chosen to go through a lottery. So she dressed as an alien to show the world that space travel was dangerous and then says that she switched the tests and said Shaggy is really the one who scored the highest, much to everyone's shock, including Velma. She then left them all to die, due to the explosives she hid on the resort, and heads back to Earth alone claiming that returning as a hero would give her all the money she could ever make. However, the gang escapes with a second spaceship made by Sly's brother Hudson, who planned to use it to return home and the heroes return to Earth and confront Shannon by showing the world her confession and she is taken to prison.
- Shannon is one of the most dangerous villains the Mystery Inc gang has ever faced; she manipulated everyone from the beginning and almost destroyed Daphne and Velma's friendship.
- The alien is based on the Xenomorph from the film, Alien.