Harley P. Gerson was a monster from Monsters, Inc., and an employee at Monsters, Inc. He has orange and yellow skin, with two large feet. He has sharp teeth, a large mouth and no arms. When he was a scarer, he was at the bottom of the Scarer's Leaderboard. He was also seen at Harryhausen's among the panicking public when Boo appeared.
The growl that Harley makes in his appearance at Harryhausen's is a sound effect taken from the 1994 video game Tekken when the character King is hit lightly.
Harley's last name, Gerson, could be a possible reference to Daniel Gerson.
For some reason, Harley Gerson didn't have a Scare Card.