Marauders

The Marauders were a group of four Gryffindors who attended Hogwarts from 1971-1978. These four students had a knack for rule-breaking and mischief making. They were James Potter, Remus Lupin, Sirius Black, and Peter Pettigrew.

Aside from making trouble, the four of them were best friends. In fact, upon finding out that their friend Remus was a werewolf, the remaining three decided to become animagi so that they could accompany their friend when he transformed.

They accomplished this task, and would meet Remus Lupin in the Shrieking Shack on the nights he transformed in their own animal forms.

Sirius' animagus form was a great big black dog. James' animagus form was a stag. (which is a male deer) and Peter's form was a rat.

The group of them gave each other nicknames that corrosponded with their animal forms.

Remus Lupin = Moony James Potter = Prongs Sirius Black = Padfoot Peter Pettigrew = Wormtail

Those nicknames transfered over into their mischief making lives, and when they created the Marauders' Map They introduced it in the following way: "Messers Moony, Wormtail, Padfoot, and Prongs proudly present: The Marauders' Map"