He was bitten by the vicious werewolf Fenrir Greyback when he was a small child, and became infected with lycanthropy; the condition being incurable, he was doomed to live his life as a werewolf.
Remus John Lupin was an only son of Lyall and Hope Lupin (née Howell). At the age of 4, he was bitten by the foul werewolf Fenrir Greyback when his father-Lyall Lupin- insulted all werewolves. Fenrir tried to kill him but Remus got saved by his father. However he became a fully fledged werewolf.
3. Lupin was turned when he was only four years old. Remus was turned by Fenrir Greyback, who sought revenge on his father for his unkind words about the werewolf community.
He turned Remus Lupin into a werewolf
Even worse, Greyback only targeted Remus because his father, Lyall, had insulted werewolves. Lyall spent the rest of his life trying to find a cure for his son, while Greyback boasted about his actions.
Greyback attacks Remus in revenge for Lyall's unguarded comments that werewolves are “soulless, evil, deserving nothing but death.” Shortly before Remus's fifth birthday, the tenth of March, Greyback breaks into Remus's bedroom and bites him.
In Harry Potter and the Deathly Hallows: Part 2, Hermione's Stunning Spell sends Greyback off the Viaduct Courtyard to the ravine below and to his death after he was discovered mauling Lavender Brown.
Both Lupin and Tonks die in combat, killed by Dolohov and Bellatrix Lestrange, respectively, leaving Teddy an orphan with Harry Potter as his godfather and Andromeda Tonks as his guardian. JK Rowling has since stated that she originally intended for both Lupin and Tonks to survive.
His savagery and evil surpass Voldemort, but he lacks the magical knowledge, ability and intellect that would allow him to be an ambitious Dark Wizard like his master.
Fenrir Greyback is, perhaps, the most savage werewolf alive today. He considers it as his mission to bite and to contaminate as many people as possible; he wants to create enough werewolves to overcome the wizards. Voldemort has promised him prey in return for his services.
Lupin never felt at ease about his love for Tonks, continuing to think that he was being cruel and selfish. Nonetheless, they married quietly in the north of Scotland, with witnesses taken from the local wizarding tavern.
Snape hears Lupin admit this while hiding under the Invisibility Cloak and also hears Lupin explain that he was not part of Sirius's joke. Snape still thinks Lupin is helping Sirius, however, and attacks Lupin. He then lets slip that Lupin is a werewolf the next morning.
Simply put, Professor Severus Snape didn't trust Lupin, thought that he was helping Black into the Castle, and set the essay because he thought someone among the third years would be able to recognize he was a Werewolf.
Remus is a werewolf, something that Lily probably knew in her sixth or seventh year when she started to get to know James better. And she wasn't frightened by him, at least not in the end. She saw in Remus what he couldn't see in himself, a person worthy of friendship, trust and maybe even love.
Yes, Dumbledore knew that Lupin was a werewolf. Due to his knowledge of Remus' lycanthropy condition, Albus Dumbledore even visited him personally to invite him to Hogwarts a Defence Against the Dark Arts teacher. Dumbledore even arranged for Snape to make Lupin the Wolfsbane Potion every fortnight.
Bill is viciously mauled by the werewolf, Fenrir Greyback. Fortunately, as Fenrir was not transformed at the time, Bill did not become a werewolf, though Madam Pomfrey is unable to completely heal his face, and he remains permanently scarred.
When Remus turns into a werewolf in The Prisoner of Azkaban, Harry, Ron, and Hermione encounter a hairless, emaciated wolf. This proves that Remus has been suppressing his inner wolf all his life, hating every bit of his affliction and living in constant fear that he will kill someone when out of his right mind.
While we don't know exactly what happened to Draco in between books five and six, fans speculated that he was bitten by werewolf Fenrir Greyback upon Voldemort's orders. This is the same evil werewolf that bit Remus Lupin as a child, permanently throwing him to the wolves.
British actor David Legeno, who played a werewolf in the Harry Potter movies, has been found dead in Death Valley, United States police said. He apparently died of "heat-related issues," the local sheriff said, after the 50-year-old's body was found near Zabriskie Point, a famed movie-related panorama spot.
In 1998, Fred participated in the Battle of Hogwarts, defending the castle's passageways with his twin. While fighting alongside his brother, Percy, he was killed in an explosion possibly caused by Death Eater Augustus Rookwood.
Peter Pettigrew
He definitely ranks at the top of those who should be regarded as the most evil members of the Death Eaters, if for no other reason than that he was more than willing to betray Lily and James to their certain deaths at Voldemort's hands.
1 Lord Voldemort
Lord Voldemort is the scariest villain in Harry Potter, if only because he is the series' overreaching villain who successfully evades death more than once.
Colin was expelled from Hogwarts in his sixth year, due to Voldemort's policy of not allowing Muggle-borns to attend the school. On 2 May, 1998, he snuck into the Room of Requirement with the rest of Dumbledore's Army and fought in the Battle of Hogwarts, during which he was killed by Yaxley.
Hedwig's killer is not explicitly identified, so he/she may have appeared in other books, films or video games, but the only known appearance is Harry Potter and the Deathly Hallows and Harry Potter and the Deathly Hallows: Part 1. A popular fan theory based on book canon suggests that Snape may have killed Hedwig.
Ron, Harry, and Hermione assume she is upset over Sirius' death, and Harry even suggests that Tonks may have been in love with him, which is why she's so crestfallen. It is only at the end of the book that we find that it is Lupin, rather than Sirius, who is the object of her affections.