The Sopranos, one of the most iconic television series of all time, left viewers with a glaring question: Why did Tony kill Christopher?

In the final season of the show, Tony Soprano, head of a notorious crime family, murders his nephew and soldier Christopher Moltisanti. The audience was left wondering about the motive behind this significant death. In the episode "Walk Like a Man," Tony and Christopher are seen joking around and appearing to be on good terms. However, the dark underbelly of the criminal world catches up with Christopher, which ultimately leads to his demise in the episode "Kennedy and Heidi. " Although the show doesn't provide a clear answer, The Many Saints of Newark, an HBO prequel movie, sheds more light on the background of Tony and Christopher's relationship. Interestingly, Christopher serves as the narrator of The Many Saints of Newark, even from the afterlife.

Just as Tony was haunted by his past deeds, karma caught up with Christopher, and his death was a consequence of his actions. 

In conclusion, the question of why Tony killed Christopher is finally answered through a combination of subtle hints, emotional character arcs, and haunting narrative choices. The Sopranos, with its intricate storytelling and multi-dimensional characters, continues to captivate audiences even years after its final episode aired.