In "Dune: Part 2," Baron Vladimir Harkonnen was stabbed to death by his grandson. This differs from the book, where a hyper-intelligent knife-wielding toddler slew the baron.
The difference is due to other inconsistencies between the movie and the book. Jessica is pregnant throughout the film, but in the book, she gives birth to her daughter, Alia.
Alia is rather creepy. She was exposed to the Water of Life while still a Fremen, which made her supernaturally wise, and she holds the memories of all her ancestors.
As Alia is still in the womb throughout the movie, Paul delivers the killing blow instead. The change is not too surprising, as the baron's death scene was somewhat anti-climactic.