Stephen Hillenburg, the creator of the children's cartoon "SpongeBob SquarePants," which became a beloved world-wide phenomenon, has died at age 57, US television network Nickelodeon said Tuesday.

Hillenburg had announced last year that he was diagnosed with amyotrophic lateral sclerosis (ALS), a neurodegenerative disease.

"SpongeBob" depicts the life of a goofy and excitable oceanic sponge along with his best friend, a starfish named Patrick, and a host of other colourful characters.

The show - first aired in 1999 - is one of the longest-running US television series and has won numerous awards, including multiple Emmys, and grown into a multibillion-dollar franchise. It has been dubbed or sub-titled in more than 60 languages, including Urdu, Azerbaijani and Maori,

"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," Nickelodeon, which broadcasts the show in the US, said in a tweet.

Actress Lori Alan, who voiced the character of Pearl on the show, said the cast and crew were "devastated."

"I can't put into words how grateful I am to you for changing my life with your creative brilliance and huge heart," the 52-year-old added.

"Phineas and Ferb" co-creator Dan Povenmire, who worked on "Rocko's Modern Life" and "SpongeBob" with Hillenburg, tweeted an article about his friend's death with the caption, "This is the saddest day."

The creator of "The Fairly Odd Parents," Butch Hartman, said he had "no words" to describe the loss.

"Steve Hillenburg was a friend and immensely talented creator. We grew up together at Nickelodeon," Hartman wrote on Twitter, adding "You will be sorely missed, Steve."

After graduating college, Hillenburg became a marine biology teacher in California, Nickelodeon said in a statement.

"This interest, combined with his artistic talent and love of the sea and its creatures, led him to write and illustrate stories as teaching tools with colorful characters that would later become the denizens of Bikini Bottom," the network said, referring to the setting of "SpongeBob."

He completed his masters in animation in 1992, going on to become creative director on "Rocko's Modern Life" before his own show launched.

"SpongeBob is a complete innocent – not an idiot. SpongeBob never fully realizes how stupid Patrick is," Hillenburg said in a 2009 interview with the Washington Post.

"They’re whipping themselves up into situations – that’s always where the humor comes from," he added.