Stephen Hillenburg, who created one of the most popular cartoons of all time with Nickelodeon's SpongeBob SquarePants, has died at age 57.
Hillenburg died Monday after a battle with ALS, Variety reports. He revealed his diagnosis in March 2017, saying at the time that he would "continue to work on SpongeBob SquarePants and my other passions for as long as I am able" and thanking fans for "the outpouring of love and support," per USA Today.
After teaching marine biology, Hillenburg got started in animation while studying at the California Institute of the Arts, going on to work as creative director on Rocko's Modern Life. In 1999, he created SpongeBob SquarePants, which quickly became a phenomenon and ran on Nickelodeon for nearly 20 years. He left his day-to-day work as showrunner after the third season and after directing 2004's The SpongeBob SquarePants Movie, but he continued serving as an executive producer. He produced a second movie, The SpongeBob Movie: Sponge Out of Water, in 2015. Nickelodeon plans to release a third SpongeBob movie in 2020.
Nickelodeon confirmed the news in a statement to Variety, saying that Hillenburg was a "beloved friend and long-time creative partner to everyone at Nickelodeon, and our hearts go out to his entire family." The network also acknowledged Hillenburg's passing on Twitter, writing that it would be "observing a moment of silence to honor his life and work."