Mole Valley resident Tom Felton, better known as Draco Malfoy from the Harry Potter films, will choose a winner in a colouring competition at a Hallowe'en extravaganza on the High Street and Swan Centre.
Thousands of people are expected to descend on the town centre between 2.30pm and 5.30pm.
As well as various ghoulish games, a Hallowe'en hunt, live scary critters and street entertainers will keep the masses entertained.
Swan Centre manager Patricia Lawless said: "We are really looking forward to what has become one of Leatherhead town centre's most popular events of the year.
"With plenty of things to see and do it's the perfect way to spend an afternoon."