Stephen Hillenburg, the creator of Nickelodeon's animated megahit SpongeBob SquarePants, died Monday. He was 57. Hillenburg died from ALS; he was diagnosed with the disease in March 2017. Nickelodoen paid tribute to him in a tweet on Tuesday: "We are sad to share the news of the passing of Stephen Hillenburg, the creator of SpongeBob SquarePants. Today, we are observing a moment of silence to honor his life and work."