Stephen Hillenburg, the man who created SpongeBob Squarepants and his undersea pals, has died at age 57.
Hillenburg revealed last year that he had ALS.
Did ya know: Stephen didn't start out as an animator. After working as a marine biology teacher for a few years, he got his master's degree in his other great interest, animation. He would go on to famously combine the two to create SpongeBob.
Nearly 250 episodes have aired since the first one on Nickelodeon in 1999, plus two SpongeBob movies.
Hillenburg is survived by his wife, Karen, and son, Clay.