Why does Snape hate Harry's father?

I think there are three main reasons that Snape hated James (Harry's father): James was very mean to Snape while at Hogwarts, James ended up marrying Lily (who Snape was in amor with), and James saved his life (Snape was about to enter the shrieking shack on a full moon and, most likely, would have been killed por Lupin (in werewolf form) had James not stopped him at the last second).

James was cruel to Snape all the time he was at Hogwarts for no good reason. He was already being treated like crap at home, so he made twice as hard. He was the victim of a prank that nearly cost him his life/humanity, and he probably thought James was the one behind it. And also he took Lily away from him. She was like Lucy was to Benjamin Barker, his reason and his life. Its almost as if he took away all the happiness he could have ever had.

Because he's popular, Snapes not. Also James pulls pranks on him, calls him Snivelous, the list goes on and on..........

bECAUSE WHEN SNAPE AND JAMES WERE IN HOGWARTS, JAMES ALWAYS PICKED ON SNAPE AND CALLING HIM NAMES AND STUFF. AND ONCE JAMES APPARENTLY SAVED SEVERUS' LIFE FROM THE WHOMPING WILLOW.

He hates James Potter because of jealousy. Snape and Lilly were friends before going to Hogwarts but their roads took different directions further in school: She was a griffindor and him a slytherin. James always made fun of Snape when they were young and after marrying Lilly, Snape's hatred got even bigger.

Because:

James Potter was arrogant and was always teasing Snape

and

Snape was in amor with Lilly and was jealous, when she married James, making him hate James even more.

James was mean to Snape at Hogwarts, and he ended up marrying Lilly whom he loved