Everyone's favorite yellow sponge, and the hero of our story. Bright, cheery, and always optimistic, SpongeBob knows how to maintain a positive attitude, even when a deadly volcano threatens to destroy his beloved town.
- Adaptational Angst Upgrade: This is probably the most vulnerable we've ever seen SpongeBob since the first movie. He constantly deals with being labeled "a simple sponge" by Mr. Krabs and the others, and wants to prove once and for all that he's good enough to be the hero that'll save Bikini Bottom (as well as the manager of the Krusty Krab, of course).
- Adaptational Attractiveness: The twiggy-armed SpongeBob is played by the very muscular Ethan Slater here.
- Adorkable: He's just as dorky and lovable as his cartoon counterpart. Slater's squeaky cartoon voice certainly adds to it.
- Big "NO!": Played for Laughs and taken Up to Eleven. He lets a colossal one out when he wakes up on the day of the eruption. As a time card gag, it ends up lasting for fifty years; he's an old man with a beard by the time he's done.
- Big "SHUT UP!": He launches one at Squidward when he interrupts his big lecture towards the others.Squidward: Deep thought, SpongeBob, but Bikini Bottom's-SpongeBob (in a low, booming voice): I'M NOT FINISHED!!!
- Break the Cutie: From suffering some serious self esteem issues to having his best friend abandon him for a cult, SpongeBob sure does go through an awful lot in the show, but his positive attitude keeps him sane and steady.
- Friendship Song: "BFF", his duet with Patrick.
- Go Out with a Smile: When it appears that all hope may be lost in the end, he encourages everyone to make their final minutes "the best seven minutes ever". If they're going to die, you can bet they're going to die happy and united.
- The Heart: Sandy provides the brains, Patrick provides the brawns, and SpongeBob provides the moral support, or "management skills", as Patrick puts it.
- "I Want" Song: Slater himself calls "(Not a) Simple Sponge" this for the character. It details SpongeBob's desire to prove himself to Mr. Krabs and his fellow Bikini Bottomites by being the hero that'll save the day.
- Large Ham: Because you can't be a cartoon icon without being incredibly over-the-top.
- Mundane Made Awesome: Used as a recurring theme for SpongeBob. Throughout the show, he's treated like a "simple sponge" that doesn't have much use outside of cleaning; this is what pushes him to work even harder in his effort to save the town. During "(Not a) Simple Sponge", a group of ensemble members come out with neon kitchen sponges and form images while SpongeBob sings, adding to the idea that simple objects like sponges can be used in the most extraordinary of ways.
- The Pollyanna: Positivity is his most significant trait. No matter what situation he's in, he always keeps a positive attitude and focuses on the bright side of things. This especially holds significance in the end, when he encourages everyone to stay positive and have the Best Day Ever in the face of destruction.Chorus: It's a typical...
Chorus: A regular...
Chorus: An ordinary...
All: Bikini Bottom... Day!
- Red-Headed Hero: Ethan Slater plays him with his natural red hair, although this wasn't originally the case (see You Gotta Have Blue Hair).
- Team Normal: He serves as this to his team with Patrick and Sandy.
- Triumphant Reprise: He belts out an epic reprise of "Simple Sponge" as he climbs to the mouth of Mount Humongous.
- You Gotta Have Blue Hair: Subverted. In the Chicago run of the show, his actor wore a yellow wig, but this had since been dropped in favor of the actor's natural hair.
SpongeBob's simple-minded starfish friend. He may be dumb and lazy on the outside, but inside, he just wants someone to listen to what he has to say.
- Adaptational Angst Upgrade: All the big guy wants is for someone to listen to him for once, and it's implied that this issue stems from the others treating him like an idiot.
- Big Damn Heroes: He swoops in on Sandy's jetpack and saves SpongeBob from falling off the mountain.
- The Big Guy: His role in the Power Trio with SpongeBob and Sandy.
- Bumbling Sidekick: He's SpongeBob's totally clueless BFF.
- Friendship Song: "BFF", his duet with SpongeBob.
- Gospel Revival Number: His centric song, "Super Sea Star Savior", has a chorus of sardine followers sing praises for their new star-shaped savior. It gets hilarious when he starts "annointing" his brethren and wears a pointed pink hat that's similar to that of the Pope's.
- Hawaiian-Shirted Tourist: This is visually emulated by his costume, which consists of a pink Hawaiian shirt, a tie-dye tee, and green shorts.
- "I Am Great!" Song: "Super Sea Star Savior" eventually becomes this. At first, Patrick is weirded out by the fact that the sardines are singing about him, but as the vast amount of attention starts sucking him in, he eventually joins in on the fun and basks in his newfound glory.
- Mighty Glacier: SpongeBob recruits him into the team because his brute strength will prove useful for the trek up the mountain.
- Mythology Gag: Two of them.
- After his sardine cult praises him for his "words of wisdom", he remarks, "Finally someone understands the inner machinations of my mind are an enigma".
- When volunteering to be a part of the band for the big finale, he asks if mayonnaise is an instrument.
- Singing Voice Dissonance: Danny Skinner is pretty good at emulating cartoon Patrick's deep speaking voice, but his natural singing voice is much higher, with a prominent southern twang.
- You Gotta Have Blue Hair: He sports pointed pink hair (originally a pompadour in the Chicago preview) that represents his pointy starfish head.
A brainy and athletic Texan squirrel who came to Bikini Bottom for a research project. She acts as SpongeBob's most trusted ally on their quest to stop the volcano from errupting, using her vast amount of scientific knowledge and brilliant inventions to aid the mission.
- Action Girl: She's a tough-as-nails karate expert who uses her abilities to trek to the top of Mount Humongous alongside SpongeBob.
- Adaptational Angst Upgrade: Big time. This version of Sandy is the victim of Fantastic Racism, with Old Man Jenkins and his mob pinning all their problems on her for one insignificant reason: she's a land creature. She also reveals that back in Texas, she was outed by her comrades for being an intelligent girl squirrel who knew karate, which is part of the reason why she moved to Bikini Bottom in the first place (this wasn't the case in the cartoon).
- Afro Asskicker: Sports an afro in the show, and is quite the asskicker.
- All of the Other Reindeer: Whether she's in Bikini Bottom or back home in Texas, she's always treated like an outcast by at least one particular group.
- Fantastic Racism: The driving force of Sandy's personal conflict. Plankton convinces Old Man Jenkins and the others that she's a problem because she "isn't even from here". It escalates to the point where someone leaves out a particularly offensive sign that reads "Land mammals go home!" Thanks to some much needed encouragement from her friends, however, she learns to fight through the hatred, and promptly kicks the sign in half.
- Named by the Adaptation: She's given the middle name Jennifer in the show.
- Pep-Talk Song: "Chop to the Top", in which Sandy encourages SpongeBob to hone his karate skills and chop his way up the mountain.Sandy: You gotta chop to the top that you aim for, get some gumption, and you won't turn tail. Just keep your eyes on the prize that you came for, and use karate, and you cannot fail...
- Pragmatic Adaptation: She doesn't wear a bulky scuba suit and helmet here. Instead, she wears a sleek white jumpsuit.
- The Smart Girl: Has an expansive knowledge of science and technlogy, and uses her skills to craft a bubble device that's powerful enough to stop any volcanic eruption.
SpongeBob and Patrick's cranky, clarinet-playing neighbor. He has a very gloomy outlook on life, beliving the worlds a horrible place filled with fear, suffering, and despair", but nonetheless, he dreams of becoming a famous stage star for the sake of his late mother, and is willing to do just about anything to achieve his big break.
- Adaptational Angst Upgrade: His hunger for stage performing is the result of a rough childhood where he was bullied and labeled a "loser" for his passion. His mother was his only support system, and her eventual passing further fueled his ongoing quest for stardom.
- Berserk Button: He'll wig out on anyone who dares to call him a loser.
- Broken Bird: Turns out Squidward's need to perform stems from his childhood trauma of being made fun of by his classmates.
- Camp Gay: The musical's version of Squidward personifies this, as he is much more flamboyant than his cartoon counterpart. While Squidward has always loved dancing and theatrics, this is the only time he has donned a sequined suit, played a pink clarinet and danced with a chorus line composed primarily of men in drag. Critics have even compared Gavin Lee's interpretation of him to Paul Lynde.
- Confusing Multiple Negatives: All of the lyrics in "I'm Not a Loser" pretty much consist of only these.
- Eleven O'Clock Number: He finally gets his chance to shine in the big showstopping tap number, "I'm Not a Loser". With a dazzling sequin suit, a big flashing "SQUIDWARD!" sign, and entire sea anemone chorus line accompanying him, it truly is the big break he's been waiting for... at least until he realizes that it was all in his head.
- "I Want" Song: "I'm Not a Loser" is this at its core, as it's really about him wanting to be somebody in the world.
- Suspiciously Specific Denial: In "Loser", his Confusing Multiple Negatives poorly hide the fact that he really looks down on himself.Squidward: My life's not empty, they don't not like me at all. I don't not leave the house, 'cause I don't not prefer to stay at home.
- Tsundere: He's this towards SpongeBob, as per usual. In fact, his negativity is used solely to be a foil to SpongeBob's positivity, which is a major running theme in the show.
- You Gotta Have Blue Hair: Curiously enough, he sports blue hair in the show, despite his cartoon self being bald.
The greedy owner of the Krusty Krab, and employer of SpongeBob and Squidward. While everyone is off panicking about Bikini Bottom's imminent doom, he decides to strike the iron while it's hot and puts on a huge "apocalypse sale" at his restaraunt, exploiting the fear of his fellow fish to make him even richer.
- Duet of Differences: "Daddy Knows Best", his duet with Pearl. While Krabs is busy singing about his fat stacks of cash, Pearl is off to the side contemplating about his greedy attitude.
- Money Song: It can't be a musical about SpongeBob without a big number for Mr. Krabs about the joys of money. In this case, it's "Daddy Knows Best", in which he tries convincing Pearl that money is the most important aspect of life. He then proceeds to open just about every nook and cranny in the Krusty Krab to show where he secretly stashes all his cash.
- Overprotective Dad: Sure he's greedy and selfish, but he still genuinely cares for his daughter Pearl, and worries for her safety when she expresses interest in following the Electric Skates on their concert tour.
- Red Boxing Gloves: His crab claws are portrayed as oversized boxing gloves.
- Skewed Priorities: It seems to be a Running Gag. Upon hearing about the volcano, the very first thing he worries about is the fact that the Krusty Krab has to close for the day, then he rushes home with Pearl to make sure his money's okay. Later, he reminds everyone that they only have one day left until their world is completely obliterated, and therefore, they should pick up some Krabby Patties while they still can.
- You Gotta Have Blue Hair: He sports red hair, and a red beard to match.
Mr. Krabs' teenage whale daughter. Even though her father spoils her silly, she deeply detests his greed and wants him to proritize his family, not his profits. She's also a huge fan of the famous rock band the Electric Skates, and eventually plans to run away with them after she's had enough of her dad's neglect.
- Adaptational Angst Upgrade: In the cartoon, she simply detested her father for being cheap. In the show, she's sick of his greed and his Skewed Priorities, and wishes for him to love her the way he loves money.
- Adaptational Dye Job: Originally a blonde, she's shown sporting black hair. This is justified however, since her hairstyle is supposed to represent Cartoon!Pearl's giant whale head.
- Daddy's Girl: Just like the cartoon, although she wishes to be more independent with her life.
- Duet of Differences: "Daddy Knows Best". While her dad is off praising the power of money, she steps aside and expresses her concerns for his ongoing greed, claiming that she should be more important to him than the endless amounts of dough that he rakes in every day.Pearl: I should be my daddy's greatest prize. But instead, he's got dollar signs in his eyes.'
- Phoneaholic Teenager: She's on her shellphone an awful lot at the beginning. In fact, the very first thing she does onstage is call her friend with an excited "HEY GIRL!"
- Tiny Guy, Huge Girl: Being a whale, she towers over her crab father; this effect is achieved through a pair of giant high tops that her actress wears.
The scheming owner of the Chum Bucket who has big plans for world domination. He uses the Mount Humongous disaster to his advantage by convincing everyone to leave Bikini Bottom and settle into a new town, where he'll tyrannically take them over as their new Evil Overlord. But they don't know that, of course...
- Adaptational Attractiveness: Due to him being personified by an onstage actor this time around.
- Big Bad: As per SpongeBob tradition, he's the main villain of the story. While Mount Humongous is the show's primary source of conflict, it's because of Plankton's Evil Plan that things start to go south by the end.
- Big Damn Kiss: He shares one with his wife Karen when his plan is about to succeed.
- Evil Counterpart: To SpongeBob. They come up with two completely different plans for the crisis at hand: SpongeBob wants to save Bikini Bottom, while Plankton wants to abandon it and seek new grounds elsewhere. They also go through similar personal struggles, SpongeBob worries about being labeled a simple sponge, while Plankton worries about being small.
- Evil Laugh: What else could you expect from an evil mastermind? "MWAH HA HAAA!!!"
- Evil Plan: He wants to move everyone to a new town, hypnotize them en masse, and become their supreme ruler in their new society.
- Eyepatch of Power: Since the character is known for only having one eye, the actor portraying him sports an evil-looking eyepatch.
- Good Hair, Evil Hair: He sports two black ponytails that represent his antennae.
- Mythology Gag: When Karen shows him the Avalanche Maker 3000 (which they attempt to use on SpongeBob and Sandy), he exclaims, "It's evil, it's diabolical... it's lemon-scented!"
- HeelFace Turn: After his Evil Plan fails, he's touched by SpongeBob's words of encouragement and joins the rest of the cast for "Best Day Ever" and the finale.
- Piss-Take Rap: Downplayed with his Villain Song, "When the Going Gets Tough", since it was written by real life rapper T.I.
- Take Over the City: What he plans on doing once everyone evacuates to a new land.
- Villain Song: "When the Going Gets Tough" is his big rap number, and he uses it to persuade everyone in Bikini Bottom to get the heck out of town and start a new life in a new place, which he's planning on taking over anyway.
A waterproof supercomputer who is Plankton's snarky sidekick and wife. She aids her husband in his plot to take everything over after realizing that his Evil Plan is putting the spark back into their relationship.
- Adaptational Attractiveness: She's personified into a glasses-wearing secretary type in a metal dress, although she does occasionally wheel around a prop of her computer self.
- Adaptational Villainy: In the cartoon, she's a neutral-sided Anti-Villain who helps Plankton with virtually no enthusiasm, and even finds herself siding with the heroes on certain occasions. Here, she's 100% villain, and is more than happy to help her husband achieve world domination. Heck, she actually hatches a plan to kill our heroes with an avalanche, something that Cartoon!Karen would never deliberately do. In The SpongeBob SquarePants Movie, the worst thing she does is brainwash everyone in Bikini Bottom to be a slave to her husband.
- Beehive Hairdo: The actress personifying her sports a large purple beehive, adding to her Sassy Secretary gimmick.
- Evil Counterpart: To Sandy. She's the brains behind Plankton's operation, and attempts to use their own gadget, the Avalanche Maker 3000 (a foil to Sandy's Eruptor Interruptor), to kill the heroes as they make their way up the mountain.
- HeelFace Turn: Along with her husband, she forgoes her evil ways in the end and joins in on the celebration.
- One-Way Visor: She wears one in her first scene, before ditching them for some pointed glasses.
- Sassy Secretary: She acts as one at first, with her costume being visually inspired by this trope (specifically with the Beehive Hairdo and pointed glasses). She starts evolving into a Sexy Secretary once her relationship with Plankton heats up.
SpongeBob's teacher at Boating School, an underwater school where students learn to drive boats like cars. She and SpongeBob are on an endless quest to get him a driver's license, but due to his unintentional recklessness behind the wheel, they are never successful.
- The Alcoholic: She slowly evolves into a drunken wreck as she drinks more kelp juice (see below for context).
- Demoted to Extra: She's one of the main characters in the TV show, but does not play a large role in the plot here.
- Drowning My Sorrows: She figures that the best thing to do during the crisis is live out her life to the fullest, so she gets wasted on kelp juice.
- Getting Crap Past the Radar: Yes, Mrs. Puff gets drunk in the show. She's just drinking kelp juice, but she orders it from a bar and acts like a straight up alcoholic because of it.
The pirate president of the SpongeBob fan club. Eager to see his idol star in his very own Broadway musical, Patchy sets up his own little VIP seat right in front of the stage, before getting booted out by security guards. He constantly tries sneaking his way back into the theater throughout the majority of the show.
- Adaptational Angst Upgrade: Played for Laughs. Like Sandy, Patchy has to deal with a lot of Fantastic Racism towards pirates, or so he claims. He even has an entire number detailing the struggles that his kind has to go through.
- Arson, Murder, and Jaywalking: He and his crew complain about all the trials that pirates have to go through, such as bad hygiene, little to no food on ships, and unbelievably slow internet connections.
- No Fourth Wall: He exists outside of the world of the musical, being an audience member and all. Therefore, he speaks directly to the audience at all times.
- Pun: He attempts to film the show in order to make a pirate copy.
- Running Gag: Him being kicked out of the theater and subsequently sneaking back in. In the end, he successfully crashes onto the stage and joins the rest of the cast for the finale.
The overbearing mayor of Bikini Bottom. She claims that everything is under control as the apocalypse draws nearer, but it's pretty clear that she has absolutely no idea what to do... so she decides to become a dictator.
- Canon Foreigner: While the cartoon did feature a few mayor characters in past episodes, this mayor is a completely original creation.
- Evil Overlord: She pretty much goes insane by Act II, and becomes a domineering dictator who rules with an iron fist and forces everyone to obey her every whim.
- FaceHeel Turn: She's not exactly a bad person in Act I, just an incompetent one. That all changes in Act II when she becomes a psychotic, power-hungry tyrant.
- Karma Houdini: She pretty much gets away with treating everyone like slaves. The most we ever get out of her is a half-assed apology.Mayor: I should probably apologize for my flagrant abuses of power. Mistakes were made.
- No Name Given: She's only credited as "The Mayor".
- Take That!: She's intended to be a jab at government officials in general, although her method of "governing" (tweeting on her phone) and her distrust in the "dishonest media" does bring a certain person to mind.
- You Gotta Have Blue Hair: Her hair is a shade of purple.
The head anchor of Bikini Bottom News. He keeps everyone up-to-date on the current state of their doomed hometown.
- Ascended Extra: His role in the TV show is relatively small, only popping up for a few minutes in certain episodes. Here, he's a prominent recurring character.
- Badass Baritone: Musically, at least. Remember that deep opening stanza from David Bowie's "No Control"? He sings that part.
- Stealth Pun: Perch Perkins is a bass.note
- Minor Character, Major Song: He has the honor of leading "No Control".
- This Just In!: He keeps the audience informed on the state of Bikini Bottom through his news program.
A muscular lobster who spends most of his time "getting his claws swole". He eventually becomes the Mayor's bodyguard.
- Adaptational Jerkass: Cartoon!Larry may have been cocky, but at least he had a friendly relationship with SpongeBob. In the show, he seems to be a bit of a bully towards him, at least at first.Larry: Watch where you're going, puny dude!
- Adaptational Personality Change: He's a mix between a Surfer Dude and a Jerk Jock here, while the original character was just an egotistical muscle.
- The Dragon: He becomes the Mayor's personal bodyguard in Act II, zapping anyone who doesn't abide by her rules.
- Improbable Weapon User: His weapon of choice as the Mayor's right hand man? A jellyfish on a stick, which he uses to prod or tase people.
- Jerk Jock: He comes off as this at first, but he gets friendlier by the end.
- Surfer Dude: Unlike his cartoon counterpart, he speaks with a distinct "gnarly" accent.
- You Gotta Have Blue Hair: He sports red dreadlocks.
A cranky old fish who leads an Angry Mob against Sandy for being a land creature.
- Adaptational Jerkass: In the cartoon, he's a Grumpy Old Man at the very worst. Here, he becomes a Fantastic Racist who shows hostility towards Sandy, though to be fair, this was mainly due to Plankton's influence, and Jenkins only targeted her because he was looking for someone to blame for the crisis.
- Angry Mob: He ends up being the leader of one against Sandy.
- Fantastic Racism: He blames Sandy for the volcano simply because she's a land creature.
- HeelFace Turn: After trying to chase her down for the entirety of the show, he thanks Sandy for saving Bikini Bottom, and happily welcomes her with open fins.Old Man Jenkins: It's always been the Bikini Bottom way that everyone's welcome here.
A famous rock band who's hired to perform at the Bikini Bottom benefit concert. Pearl's a huge fan of these guys. They're known to rock out while zipping across the stage on skateboards and roller skates, hence the name.
- British Rockstar: How they were originally portrayed in the Chicago production. They eventually switched to American accents in later shows.
- Canon Foreigner: They don't appear in the original cartoon.
- Jerkass: In actuality, they're a trio of stubborn, self-important bullies who treat Squidward like total crap and force him to follow their absurdly long list of demands.
- Minor Character, Major Song: They have an entire musical number in the form of "Bikini Bottom Boogie", but only appear in three scenes.
- Rock Trio: They're a three person band.
- Shout-Out: They were originally modeled after 80's era Aerosmith, a tribute to Steven Tyler and Joe Perry, who wrote "Bikini Bottom Boogie". In the Broadway production, however, they were given a punked out, Green Day style makeover.
- Suddenly SHOUTING!: Played for Laughs. One member constantly yells "ROCK AND ROLL!", apparently due to a bad stage accident.