The movie: Spaceballs (1987)
The player(s): Mel Brooks

The man child in question here is not one of the film's stars, but its director, the perpetually childlike Mel Brooks (though he does have a role in the film, as President Skroob). His 1987 Star Wars parody is a tribute to the longtime and growing number of fanboys whose lives revolve around George Lucas' sci-fi franchise, with a few appropriately immature tweaks: Han and Luke are one character (Lone Starr), Princess Leia has become Vespa, Darth Vader is simply known as Dark Helmet and the cuddly wookie played by John Candy is Barf.