James Potter was a Pure-Blood wizard born on 27th March, 1960. He attended Hogwarts School of Witchcraft and Wizardry and was sorted into Gryffindor House. He married Lily Evans and was the father of Harry Potter. The series starts after his death.
On the Hogwarts Express he met a boy called Sirius Black who he quickly became friends with. He also met Lily Evans for the first time as she was sitting with Severus Snape and they got off to a bad start. James and Sirius became friends with Remus Lupin and Peter Pettigrew to form a group called the Marauders. His nickname in the group was Prongs.
James was magically gifted and when he discovered that Remus was a werewolf, he and the other Marauders worked during their school years to become illegal unregistered Animagi. James took the form of a stag when he transformed.
James was a reputed troublemaker at school and would bully Snape. He and Sirius received many detentions over the years for various offenses. They were also funny and would make Madam Rosmerta laugh when they were in Hogsmeade. However after his fifth year at school James seems to have made a turn around in his behaviour enough to be made Head Boy without having been a Prefect. However he would still attack Snape.
After school he became a member of the original Order of the Phoenix. He married Lily Evans and Sirius was best man at his wedding. However before their first child was born Albus Dumbledore heard Sybill Trelawney make a Prophecy that indicated that their son would be the one to destroy Voldemort. As Snape had overheard part of this Prophecy and would report it to Voldemort, Dumbledore encouraged them to go into hiding. They moved into Godric's Hollow and the Fidelius Charm was used on their house.
Albus Dumbledore, suspecting that someone close to them was a spy, offered to be Secret Keeper for them. However James and Lily placed their faith in Sirius. Sirius believed that his known close friendship with the Potters made him an obvious target and as a bluff persuaded them to make Peter Pettigrew Secret Keeper in his stead. He didn't nominate Remus suspecting him to be the spy. Sadly it was Pettigrew who was the traiter and he gave Voldemort the Potters' whereabouts. Voldemort came to kill their son and murdered both James and Lily before turning his wand on Harry, who's protection from his mother's sacrifice cause Voldemort's spell to backfire.