Who is the man on the moon they all speak to?

By the official website, The Guardians of Childhood, he is known as MiM. He is actually a being from another place that has vowed to protect earth children from Pitch knowing first hand what Pitch did to himself.

According to the book basically the royal family had a battle with pitch and their rocket ship thing turned into the moon and the man in the moon is the son who was on the ship when it changed into the moon.

Not even a close answer :3

The man in the moon is a woman. Her name is Mama Quilla the Incan goddess of the moon. The guardians was her gift to the Incans. She wanted to spread that similar protection she recieved from them to all over the globe. :3

Sorry just a made up Idea I created when I wrote a fanfic about 10 different gods and goddess of 10 different ancient civilizations who monitor the Earth under a higher power, (for me God)

Well... According to the Rise of the Guardians Wiki, Tsar Lunar is the name of the Man in Moon a.k.a MiM...

It says that he is the very first Guardian who lived on the moon and protected the dreams of all children his ship. In the movie, he is shown to be a silent, but active, observer of the transpiring events.

Hope i have given you the answer you were looking for.. :)

Tsar Lunar ! He was born after some time after pitch turned into ... Pitch . I TOLD YOU PITCH WAS OLDER !