The Marauders
I solemnly swear that I am up to no good.
THE
MARAUDERS'
MAP
Marauders 
Hogwarts Profile
MOONY
Remus Lupin was first introduced in the third book, Harry Potter and the Prisoner of Azkaban (Chapter Five: The Dementor), as Hogwarts' new Defense Against the Dark Arts professor.
The name Professor R. J. Lupin was stamped across one corner in peeling letters.
"Wonder what he teaches?" said Ron, frowning at Professor Lupin's pallid profile.
"That's obvious," whispered Hermione. "There's only one vacancy, isn't there? Defense Against the Dark Arts."
It was later revealed in Chapter Seventeen (Cat, Rat, and Dog) of the third book that Lupin is not just an ordinary man.
"You're wrong," said Lupin. "I haven't been Sirius's friend, but I am now -- Let me explain...."
"NO!" Hermione screamed. "Harry, don't trust him, he's been helping Black get into the castle, he wants you dead too -- he's a werewolf!"
He is indeed a werewolf, bitten by Fenrir Greyback when he was just a little kid. There is always discrimination, even in the wizarding world. Because of his "furry little problem" as James Potter casually puts it, Lupin does not have a permanent job and therefore does not have the money to buy more than what he needs.
"The stranger was wearing an extremely shabby set of wizard's robes that had been darned in several places. He looked ill and exhausted. Though quite young, his light brown hair was flecked with gray."
Remus Lupin is considered as the most mature and responsible Marauder. Being appointed as a Prefect when they were fifth years and later on a future professor, it goes to show that he is a sensible and reasonable person. But despite of those characteristics he shows, he is a true Marauder at heart.
He married Nymphadora Tonks, who prefers to be called with her surname, in the year 1997. They had a son named Teddy Remus Lupin, Harry Potter's godson.
Remus Lupin died on May 2, 1997 with his wife Tonks, during the Battle of Hogwarts. He was the last Marauder to pass away.
"...As Ginny and Hermione moved closer to the rest of the family, Harry had a clear view of the bodies lying next to Fred: Remus and Tonks, pale and still and peaceful-looking, apparently asleep beneath the dark, enchanted ceiling." - Harry Potter and the Deathly Hallows, The Prince's Tale
WORMTAIL
Peter Pettigrew was first mentioned in the third book, Chapter Ten: The Marauder's Map, as one of the persons Sirius Black has killed after James and Lily's death by Voldemort's hand.
"Alas, if only we had," said Fudge bitterly. "It was not we who found him. It was little Peter Pettigrew -- another of the Potters' friends. Maddened by grief, no doubt, and knowing that Black had been the Potter's Secret-Keeper, he went after Black himself."
" Pettigrew ... that fat little boy who was always tagging around after them at Hogwarts?" said Madam Rosmerta.
The wizarding world thought that Pettigrew was killed by Black.
"[...]Pettigrew died a hero's death. Eyewitnesses[...] told us how Pettigrew cornered Black. They say he was sobbing, 'Lily and James, Sirius! How could you?' And then he went for his wand. Well, of course, Black was quicker. Blew Pettigrew to smithereens...."
The biggest piece the Ministry workers have found of Pettigrew was his finger. He had received the Order of Melin, First Class because of his "courageous act".
"Hero-worshipped Black and Potter... Never quite in their league, talent-wise..."
Though a slow learner, he still managed to become an Animagus. His form is a rat, henceforth the name Wormtail.
It was later exposed in the third book that Pettigrew was not an innocent man. He became the Potters' Secret-Keeper, not Sirius. No one knew about the switch except for the four of them. Little did they know that Pettigrew was a Death Eater, that they are playing into Voldemort's trap.
After cornering Black after the attack of the Potters, he shouted at Sirius for betraying the Potters, blew up a street full of Muggles, cut off his finger, and changed into a rat. He hid as the pet rat of the Weasleys named Scabbers, first owned by Percy and was gave to Ron.
He was a coward. He came back to Voldemort because he was afraid. He helped him to have a full body back by performing a ritual that involved cutting his own hand off. As a reward, Voldemort gave him a new silver hand. His death was also a caused by that hand.
"Wandless, helpless, Pettigrew's pupils dilated in terror. His eyes had slid from Harry's face to something else. His own silver fingers were moving inexorably toward his own throat.
[...]The silver tool that Voldemort had given his most cowardly servant had turned upon its disarmed and useless owner; Pettigrew was reaping his reward for his hesitation, his moment of pity; he was being strangled before their eyes.
[...]Pettigrew dropped to his knees,[...] Wormtail's eyes rolled upward in his purple face; he gave a last twitch, and was still. - Harry Potter and the Deathly Hallows, Malfoy Manor
PADFOOT
Mischief managed.