Who kill mr whatsit in A Wrinkle Time?

It's not explicitly stated who killed Mr. Whatsit in Madeleine L'Engle's *A Wrinkle in Time*, but it's heavily implied that it was the Black Thing, the embodiment of evil that threatens the universe.

Here's why:

* Mr. Whatsit's Sacrifice: Mr. Whatsit's death is described as a sacrifice, a selfless act to protect Meg, Charles Wallace, and Calvin. He states, "There is nothing to fear. I have to go... I am needed... I go to meet the enemy."

* The Black Thing's Presence: The Black Thing is a powerful force that actively tries to corrupt and destroy. It's a force of pure evil, so it makes sense that it would be the one to kill Mr. Whatsit.

* Mr. Whatsit's Warning: Mr. Whatsit warned Meg about the dangers of the Black Thing, saying "The enemy will strike at the place where you are most vulnerable... The enemy is pure evil... He will seek to destroy the love that is in your heart." This foreshadows the potential danger Mr. Whatsit faces.

While the novel doesn't state it outright, the context heavily suggests that the Black Thing is responsible for Mr. Whatsit's demise. It's a significant event that emphasizes the conflict between good and evil in the story.