Summary
(Mammon is a rotund four-armed demon who resembles a jester. He has neon green eyes with what appears to be an eye mask, and sharp neon green teeth with a tongue that's forked and purple with at least three dark yellow stripes inside his mouth. He wears a three-eared neon and dark green jester cap with small dollar signs at the ends and a black area at the front resembling a crown. He wears a jester's collar colored half-dark green and half-neon green with yellow trim at the bottom and has black diamonds. Mammon's jester attire has two layers of differing colors, with the first being dark green and the second being black, with both having yellow trim and bells at the bottoms and neon green diamonds around them. The sleeves fit into his gloves and are asymmetric, one on each side being dark green and black while the other has white and pale blue stripes. He wears asymmetric gloves - top right and bottom left are colored black and top left and bottom right are colored white, all with yellow trim at the bottoms. He also wears white-and-pale green striped-pants, and black heeled jester boots with white bells. He carries a yellow cane topped with a large dollar sign.) (Personality Befitting the sin he embodies, Mammon is very egotistical and greedy, and he doesn't care for the well-being of others, only caring about how much he can profit from them to indulge his own greed. However, he does appear to have standards as he was not pleased of taking loose change from a poor kid. Mammon acts friendly in front of his audience just to look the part and treats Fizzarolli like a son. From what Fizzarolli has stated, Mammon is also a perfectionist. As his brand face, Mammon wants zero flaws in his brand figure whatsoever. He is also abusive, forcing Fizzarolli to do many stunts that put Fizzarolli in danger, such as being a living target for knife-throwing. However, Mammon also seems to show genuine concern over Fizzarolli when he starts having a panic attack, although it quickly changes to him looking threateningly and demanding for him to "get [his] shit together". He has a foul mouth, even more so than most demons, even saying "cunt" several times. He is also a chauvinist, publicly stating women "just ain't funny". Still, he claims to have reconsidered such comments upon seeing Glitz and Glam's performance and the twins becoming finalists. There is also an ignorant side of him, such as when Fizzarolli is singing "2 Minutes Notice", he is unable to notice that the song is about him, even after Asmodeus says it is, and only realizes when Fizzarolli calls Mammon by name. Mammon is also shown to be fairly confident in his own might, not being intimidated when Asmodeus, a fellow Sin, came to Fizzarolli's defense. Though he also shows he seemingly prefers not to fight directly, retreating when his threat to reveal Fizzarolli and Asmodeus' relationship fell flat, suggesting him to be somewhat cowardly despite his bloated ego. He is also known to be lazy as Asmodeus stated that he had not performed anymore clown acts and Blitzo called the last show he attended being an overhyped commercial. Mammon is shown to be a very vulgar and disgusting individual. He has no qualms in creating a whole line of sex toys so that everyone- adults, teenagers and even kids- can display their sexual desires and fantasies toward the clown, which as a result has made Fizzaroli be mostly a sex image and have many creeps and degenerate people follow him. Also, as one of the Seven Deadly Sins, he is haughty and somewhat snobbish. In "Mastermind" during the trial against Blitzo and his colleagues, Mammon shows complete disinterest and apathy about what would happen to them due to belonging to a lower class, even criticizing Asmodeus and Beelzebub how they "enjoy slumming out with the lower class plebs". He's also shown to have very poor manners and lack of boundaries, when the court is adjourned by Satan to have lunch, Mammon immediately begins to eat the food he brought to the court in a very rude and disrespectful manner, with Asmodeus and Beelzebub visibly disgusted with how he's eating, although he seemingly doesn't care about it.)
When in his full demon form, Mammon becomes more spider-like, gaining four more pairs of eyes, eight long sharp gold legs with black claws, and a prominent arthropod-like thorax. His jester cap's ears also become sharper. He is shorter than Asmodeus, who in full demon form has to bend down to be at his eye level.
Unlike Fizzarolli, Blitzo saw through Mammon's act early on and isn't afraid to call out his flaws to his face. When Blitzo chewed him out for how he treats Fizzarolli, Mammon was not happy with his employee bringing acquaintances to the pageant. Mammon called Blitzo a "dumpster diver" due to him being a low-class imp, showing that Mammon has a mutual dislike for Blitzo. In "Mastermind", Mammon was against Blitzo at his trial for illegally using Stolas' grimoire and was in favor of him being executed along with his crew.
Until the events in "MAMMON'S MAGNIFICENT MUSICAL MID-SEASON SPECIAL (ft Fizzarolli)", Fizzarolli was "favored" by Mammon, being Greed's brand star for multiple uses. Mammon has sold multiple Robo Fizzes by his name, and never hesitates to gaslight him into performing past his limits. Despite his insatiable love of money, Mammon does see Fizzarolli as a son to some degree. When the latter begins to crack under the pressure, Mammon allows him to take a break, but only so he can get his act together and perform properly. However, when Mammon learns that "2 Minutes Notice" is all about him, their partnership immediately crumbles. It was when Fizz publicly announced that he quit, Mammon clarified that he is like a "son he didn't want."
While brief, in "Mastermind", Mammon shows an interest towards Leviathan, asking her if she would like to go out with him after trial. While she has not said anything positive or negative about him, the left head seems to reciprocate the interest, however the right does not.
While no past interactions between the two have been revealed, Beelzebub shows visible dislike of the sin of Greed, calling him a "flaming pile of clown shit" during Blitzo's trial in the episode "Mastermind". Despite herself being the sin of Gluttony, she seems disgusted by his complete lack of manners when he eats. Mammon also uses Beelzebub as a target of ridicule for dating a pleb.
In "MAMMON'S MAGNIFICENT MUSICAL MID-SEASON SPECIAL (ft Fizzarolli)", it is shown that Asmodeus does not take kindly to him and how Fizzarolli forces himself to be a perfectionist for him. Asmodeus describes Mammon as a "selfish, manipulative, piece of shit". It is also apparent that he doesn't have a good relationship with Asmodeus, as he sees him as an embarrassment because he loves Fizzarolli. However, Mammon was caught off guard when, instead of laughing at Asmodeus, people texted and gossiped at how they knew about their relationship all along, but Mammon promised that Asmodeus would regret admitting it. Aside from their personal relationship, Mammon also has a professional one with Asmodeus, as Asmodeus admitted that he is the one who designs and manufactures the sex robots in Fizzarolli's likeness for Mammon to then sell for profit. As stated by Asmodeus, he's known Mammon since "the start of Hell", implying their long history and relationship. Due to this, Asmodeus also has a personal nickname for Mammon, "Mam". In "Mastermind", Mammon continues his conflict and contempt against Asmodeus for defending Blitzo, leading him to mock his relationship with Fizzarolli, but backs off when Asmodeus threatens him, though continued to want to argue and fight when Beelzebub joined in.
In "Loo Loo Land", it is suggested that the eponymous theme park, which Mammon owns, is mostly a rip off of a larger amusement park owned by Lucifer. It is possible that Lucifer might not hold a positive regard for Mammon, as it's mentioned that there are cease and desist letters he had sent to the Sin of Greed seen during the Loo Loo Land song. As shown in "New Pentious", Lucifer keeps multiple pictures of Mammon in his room at the Hazbin Hotel, showing a presumed fondness for his fellow Sin. In "Silenced", Lucifer received stacks of money from Mammon and a note saying it is a bribe and Mammon wants him to come back, as seen in Lucifer's Hotel room alongside gifts from other Sins. This indicates that Mammon really misses Lucifer and doesn't mind spending money to try to convince him to return.
His overall fun and jovial demeanor and behavior (in public) gathers the admiration of all his fans when he shows up, even drawing the attention of Fizzarolli.
During his entrance in a flashback, he is shown playing the guitar.
Mammon was shown to be able to generate explosions when he teleports and caused Mammon Theatre to explode at the end of "MAMMON'S MAGNIFICENT MUSICAL MID-SEASON SPECIAL (ft Fizzarolli)".
He is capable of teleporting from one area to another, which he does so with an explosion of green smoke and a charge of green lightning that turn into $ signs, with audible cash register sound effect. Though the sound effect is absent when he confronts Fizzarolli on his resignation, implying that the sound effects may be based on his mood or emotions.
He can generate green smoke from his mouth, and also when he teleports.
He can generate sparks of green electricity from his body and generate sparks of green lightning when he teleports.
As a Deadly Sin, Mammon is presumably immortal and only able to be killed by angelic weaponry. As mentioned by Asmodeus in "MAMMON'S MAGNIFICENT MUSICAL MID-SEASON SPECIAL (ft Fizzarolli)", Mammon has existed since at least the start of hell, meaning he is thousands of years old and presumably is unable to die of old age.