Nickelodeon's SpongeBob SquarePants has been going strong for over two decades now thanks to its characters. The colorful cast of Bikini Bottom presents a variety of comedic avenues, with Patrick, Sandy, Squidward and Mr. Krabs all bouncing off SpongeBob in fun, unique ways. The best contrast to his high energy is the duo of Plankton and Karen, whose repeated failures to turn their Chum Bucket into a viable rival to the Krusty Krab have fueled plenty of SpongeBob storylines and spinoffs.
Plankton and Karen have become fundamental parts of SpongeBob SquarePants. They've appeared in most iterations of the franchise in some capacity, even the upcoming SpongeBob video game The Cosmic Shake. But that wouldn't have been the case if series creator Stephen Hillenburg had agreed with Nickelodeon's original idea for the character, which would have turned the role into a one-off guest appearance for... Bruce Willis?!
How Plankton Originated on SpongeBob SquarePants
Plankton has been arguably the closest thing SpongeBob SquarePants has to a recurring villain since his debut in Season 1, Episode 3, "Plankton!" The hated rival of Mr. Krabs and the Krusty Krab as a whole, Plankton is a technically brilliant but hilariously inept super-genius, whose attempts to steal the Krusty Krab secret formula always end in disaster. Alongside his long-suffering computer wife Karen, Plankton's exploits have made up many storylines in the long-running show's history -- and the character was also the villain in The SpongeBob SquarePants Movie.
That's why it's shocking that Plankton started as a far more throwaway character. According to excerpts from the book The SpongeBob SquarePants Experience: A Deep Dive into the World of Bikini Bottom by Jerry Beck, Hillenburg didn't initially consider Plankton a member of the main cast. Instead, it was Douglass Lawrence -- a voice actor and writer on the show -- who saw his potential. Utilizing the same deep voice he'd used for bit characters in previous Nick cartoon Rocko's Modern Life, Lawrence quickly became synonymous with the character. He pitched new ideas that eventually picked up steam and led to more episodes centering around Plankton. But that also wasn't in Nickelodeon's original plans.
How Bruce Willis Almost Played SpongeBob SquarePants' Plankton
Since Plankton was conceived as a one-off character, Nickelodeon saw the potential to stunt cast the part. According to Lawrence's appearance on Nerdist podcast Big Pop Fun, the network suggested bringing in a big-name celebrity to make that single appearance. The actor suggested was Bruce Willis, who could have embodied Plankton's frustration well. But Hillenburg -- despite still being unsure of the character's long-term viability -- fought for Lawrence to stay in the role. He argued that the character worked incredibly well with Lawrence's voice -- something he and the rest of SpongeBob's creatives would further embrace over time, as Plankton became a more consistent presence in the main cast.
Still, it's interesting to consider how SpongeBob SquarePants might have been different if Plankton had only appeared once. Getting extra eyes on the show with a big celebrity casting wouldn't have been necessary, as the franchise later featured A-list stars like Scarlett Johansson and David Bowie. Plankton grew into a constant source of comedy and if Willis had come to Bikini Bottom, then all of that would have been negated. The show -- and the greater franchise -- would have been lesser for the lack of Plankton and Karen's relationship and storylines.