James Howlett aka Logan, or more popularly known as Wolverine is very possibly the all time favorite X-Men.
Wolverine is one of the ten oldest mutants to walk the Earth. Born in the late 19th century, he is the only X-Men who was born later than Jonas Graymalkin, who was born in the early 19th century. James's life began somewhere between the year 1882 and 1885, a child born out of wedlock to his mother Elizabeth Howlett, he was the son of an estate owner and lived most of his childhood on the estate in Canada. Having lost her first son, Elizabeth suffered from a mental breakdown and frequented the mental institution and due to her state of mind, James was mostly neglected by her. Living on the estate with the Howlett family was their estate caretaker and James' biological father, Thomas Logan (which is where James got the alias Logan from), and his son "Dog".
Following a series of undesired events involving Rose O'Hara, a childhood friend of both James and Dog, Dog kills James' pet puppy, and consequently the Logan family is kicked out of the estate. Thomas returns to the farm with Dog, drunk and out of control, to take his lover Elizabeth with him, and in a scuffle with her father John Howlett Sr., Thomas kills John. Seeing what had happened, James' mutation abruptly manifested, revealing claws extending from the back of his hands and him going into an animalistic frenzy. James attacks the Logans and kills Thomas, scars Dog on his face, and that, was the birth of his mutant self. As an effect of his mutation and trauma caused by the events, James' healing factor wiped out most of the traumatic memories from his mind.
After the incident, James took the name Logan to hide his identity. He and Rose ended up in a British Columbia quarry, where Logan worked as a minor and they lived together under the pretense of being cousins. The hard labor triggered more drastic changes to his body - he became more animal-like with heightened senses, and increased strength, speed, and agility. With his work ethics and unselfish personality, Logan became a favorite among the people who lived there including the foreman, Smitty. This created a conflict between one of the miners name Cookie, who was Smitty's favorite prior to Logan's arrival. The conflict escalated and Logan and Cookie were put up against each other in a cage fight. Upon defeating Cookie, Logan was given the nickname THE WOLVERINE. He remained the undisputed champion of cage fights.
Over time, Logan developed feelings for Rose but he could not make any advances because of them being thought to be cousins. Smitty too took a liking for Rose and they eventually fell in love with each other before getting engaged to each other. Logan was deeply affected by their relationship but chose to take the high road for the sake of Rose's happiness. Meanwhile, Dog had grown up to be quite a menacing man himself. He was asked by John Sr. who was very sick at the time, to track down Logan and Rose so he could meet them and make peace before he died. Dog had a different agenda and tracked them down easily. It would appear that Dog had developed some kind of natural ability for tracking, and a very muscular built. As soon as he found Logan, they fought fiercely in the middle of the street and despite being much bigger and stronger, he was no match for Logan's berserker rage. As Logan unsheathes his claws to kill Dog, Rose leaps in to try and stop him, but she is unfortunately pierced by Logan's claws. The horrific accident was too much for Logan to handle and so, he ran into the woods to live in self-exile.