Is Griphook a Bad Guy?

Personality and traits. Being a goblin, Griphook severely distrusted wizardkind and hated wizarding arrogance, stemming from the fact that goblins had been treated brutally by wizards in the past.

Does Griphook betray Harry in the book?

Griphook did betray Harry, but let's face it, Harry was going to betray him. Harry wouldn't have left Griphook to die, of course, but in the end the goblin paid the ultimate price. He was murdered by Voldemort and the sword was once again taken forcibly by wizards for their gain. ... It's not easy being a goblin, you know.

Why did Voldemort kill Griphook?

I was fairly certain at least in the movies, that griphook was killed when Voldemort had his rage fit at Gringotts after he found out the Horcrux had been stolen. In the book-Griphook and the trio break in successfully but when escaping, Griphook betrays them to the other goblins and escapes with the sword.