20He Became A Werewolf At 4
Remus Lupin's defining physical attribute is the fact that he was actually a werewolf, but the origin of his curse is even more tragic than one would expect. Lupin's father, Lyall, worked for the Ministry of Magic. During the trial of Fenrir Greyback, Lyall was the only one to realize
that he was a werewolf. Having an anger for Greyback's crimes, as well as a bigoted opinion about werewolves, Lyall demanded that Greyback be put down.
This enraged Greyback, who decided to get revenge on Lyall by attacking Remus. Although Greyback wasn't able to take out Remus due to Lyall's spells, he was able to bite him. The result was Remus being cursed with lycanthropy for the rest of his life at age 4. It was a bitter wake-up call for Lyall, who was unable to cure his son.