The funnyman, who played Jerry Seinfeld's nemesis Newman on the beloved Tv show, was the victim of a death hoax following reports he had lost his life in a car crash.
Fans flooded Twitter to pay their respects to the Jurassic Park star, who quickly responded to clear up the story.
He wrote, "Some of you will be glad to hear this, others strangely disappointed, but... I am alive and well!"
He added, "Thanks for all the love everybody. I didn't know you cared. Glad to be breathing!"
It is not clear if Knight was actually involved in a car crash.