"Don't blow your wig, Dice. If those two little finks try anything...I'll be waiting!!!"
—The Devil to King Dice
The Devil has black fur, yellow eyes with red pupils (which are only seen in close-ups), two horns on his head, gray hands and feet and large, pointed ears. He also appears to be very tall and huge. He has a tail with a pointed end in artworks, but does not have one in the game.
Much like many depictions of Satan, the Devil is a cruel and malevolent being that grants deals to anyone who asks in exchange for their souls and servitude. He can be a clever and manipulative deceitful trickster as well, turning Cuphead and Mugman into his slaves despite agreeing to spare them if they hand over all of the soul contracts. He also lacks empathy towards everyone, including his own minions, as evident by him calling King Dice a "good-for-nothing lackey" after he has been beaten.
The Devil's main trait is that he is incredibly prideful of himself, believing he'll always win in the end as he brushes King Dice off when the latter tries to warn him about the brothers becoming stronger.
Being the owner of the casino, the Devil resided in Inkwell Hell, making deals with anyone who wanted their wishes granted for the price of their souls. One day, after being impressed by the winning streak of Cuphead and Mugman at the Craps table, he approached the pair and offered them all the loot in the casino if they won the next roll. If they lost, he would claim their souls.
Cuphead, blinded by greed, threw the dice before Mugman, who was fully aware of the risks, could stop him. Be it by sheer coincidence or the game being rigged, the dice landed on snake eyes, resulting in the Devil's victory. Having lost, the brothers begged him not to take their souls and asked if there was anything else they could give him in exchange. After pondering, the Devil told them that if they can gather the soul contracts from his other debtors before tomorrow at midnight, he would spare their lives and rudely boot them out of his casino. He then sent King Dice to make sure the pair fulfill their end of the bargain.
Later, in a conversation with King Dice, the Devil proclaims that he knew there was something special about the pair after Dices reports their growing progress in collecting the contracts of the other debtors. In response to Dice's concern about Cuphead and Mugman being up to something, he assures him that he'll be waiting in case they try anything.
Eventually, Cuphead and Mugman obtain all the contracts and confront the Devil once again in his throne room. The Devil congratulated the pair for defeating King Dice and offers the choice to join him if they give him the soul contracts. If the brothers agree, he will happily turn them into demonic beings (possibly as his replacement henchmen for King Dice), revealing that he had deceived them.
If the brothers refuse, the Devil will become angry and battle them for not holding their end of the bargain. In the end, the Devil is defeated and forced to finally surrender, and all the soul contracts are destroyed by Cuphead and Mugman, thus freeing Inkwell Isles and its inhabitants from his clutches.
The Devil glares at Cuphead and Mugman, and his pupil turns into image of a cup being shattered and its shards being sliced into nothing by a cleaver, later laughing in the background. This intro is unique, because unlike in every other intro, Cuphead and Mugman are terrified instead of getting prepared for battle, reusing their scared poses from when they fail to protect the Urn in the game's mausoleum levels.
"You broke our deal...now it's my turn to break you!!!"
—The Devil, Phase 1 death screen
The Devil's first phase involves him attacking with both his trident and his transformations.
By chanting an incantation and swinging his trident, he can create one of three projectile attacks:
- Creating four crystal balls that bounce around the arena erratically. One of the four can be parried.
- Creating five fireballs with eyes that moving left to right and back; four blue fireballs revolve around one pink one, which can be parried.
- Creating six fireballs fixed in a hexagon formation, which home in on the players. One of the six can be parried.
He also uses three transformations, each with its own attack:
- Spider: The Devil grows four extra arms and detaches his head as his head grows four extra eyes, two smaller horns and four small legs to resemble a spider. In this transformation, he primarily attacks by slamming down three times before reverting to his original form.
- Ram: His head becomes a ram and he extends his arms from both sides to crush the players in the middle. This attack can be tricky, as players have to jump at the precise moment to not get hit. Formerly, the player was able to crouch to avoid this attack.
- Serpent: His head becomes a draconic serpent and extends to either side as a means to corner the players so they can be hit by his minions.
Throughout the phase, his purple demon minions hiding behind his throne will come from either side to damage the players. These minions can be disposed of by simply shooting at them. Hitpoints = 4.5/5
After taking enough hits, the Devil will pull his skeleton out of his skin and escape through a small hole in the arena's center. The players must follow him into the hole or be damaged by advancing walls of fire on either side of the screen. Hitpoints = 665/735
"Anyone who opposes me will be destroyed!"
—The Devil, Final phase death screen
After the player escapes through the hole, the final battle commences as the Devil grows into a giant and players fight him on five floating platforms. In this phase, players have to shoot at his eyes while dodging his two attacks:-
- By joining his two eyes into one, he summons a fiery axe that moves in a spiral motion and will damage the player(s) if they run into it.
- A bat bomb is created from one eye and spawned through either the left and right ears, depending on the eye he spawns them in. If the player(s) fail to neutralize the bomb by parrying it soon after it flies out of the Devil's ear, the bomb will explode covering a wide radius.
Throughout the phase, flaming poker chips will fall from the sky and land onto the platforms, damaging the players standing beneath them. These poker chips follow a pattern: if the first poker chip appears at the left, the next chip will appear at the right, vice versa if the first poker chip appears at the right. Once at the other end, it will loop back around. Eventually, the Devil will be knocked back. Hitpoints = 570/630
The Devil will be frustrated and keep looking around, the platforms will be reduced to three which increases the chance of poker chips falling onto the players. the Devil will no longer fight Cuphead and Mugman directly; Instead, he will summon his minions to damage the players in one of two ways:
- He will summon two fat purple winged demons from both sides to shoot skulls at them. Occasionally, pink skulls appear that can be parried. These demons can be shot down when enough damage is dealt. Hitpoints = 42/50
- Above his head is a group of small, blue-winged demons that home in on the players. These demons can also be dispatched fairly easily by shooting at them. Hitpoints = 3.5/3.5
After taking enough hits, the Devil will be knocked back again. Hitpoints = 475/525
The Devil will go into a physical and mental breakdown, crying. In this final sub-phase, he is reduced to using the poker chips and his own tears to damage the players. Only one platform will remain in the center as players have to dodge the falling poker chip and dash back to the platform while avoiding his tears. All of the tears can be parried.
After the Devil takes enough damage, he is beaten for good. Hitpoints = 190/210
|The Devil laughing in the bad ending.|
|The Devil's introduction.|
|The Devil laughing.|
|The Devil's ram transformation.|
|The Devil's serpent transformation.|
|The Devil's spider transformation.|
|The Devil chanting while using his trident.|
|The skeleton escapes.|
|The Devil frustrated.|
|The Devil crying.|
|The Devil defeated.|
|Normal Mode||Expert Mode|
- In the beginning of the story, he represents "double or nothing" in Craps, which Cuphead and Mugman played together. However, he added the taking of their souls if they lose the bet.
- Oddly, the changelogs list the serpent attack as "snake attack" even though it has legs and wings, making it resemble that of a Chinese dragon.
- The Devil's design is based on the devil from "Hell's Bells", a short from Silly Symphonies. In addition,the Devil's transformation into a spider is based on the spider at the beginning of Hell's Bells.
- The Devil might also be inspired by the devils in the 1934 Betty Boop cartoon Red Hot Mama.
- The depiction of hell with the Devil and his minions also resembles Pluto and his minions from the Silly Symphony cartoon The Goddess of Spring.
- His appearance may also be inspired by a portrait of him from a large book called the "Codex Gigas" or "The Devil's Bible"
- Originally, the Devil brings evil and temptations from the Bible. Like Cuphead and Mugman, they make immoral actions by playing in the casino.
- If the player agrees to give the Devil all the soul contracts, this will result in getting the bad ending where Cuphead and Mugman become corrupt minions. This is most likely a reference to the bad ending in Contra: Hard Corps in which the player is invited by Colonel Bahamut to join him.
- His last 3 stages are very similar with the battle with Majoliné from Locoroco 2, where the boss's face is huge and shoots with enemies generated by its head.
- The reaction that Cuphead and Mugman have before fighting the Devil may be an homage to the boss fights in the Battletoads series when either Rash, Zitz or Pimple (and Billy and Jimmy Lee in the Double Dragon crossover) get the same terrified reaction when facing many bosses at the start of the battle.
- There's an unused design of the Devil shown in the 2014 E3 trailer that is a vampire-like bat which fires other bats to attack.
- The Devil’s First Phase form is similar to Loki and Emperor Sardius, respectively the final bosses from Capcom’s Ghouls 'n' Ghosts and Super Ghouls 'n' Ghosts.
- The fight appears to take some influence from Disney's Fantasia. The hellish backdrop seen during the 1st phase resembles the volcanic landscape seen in the opening act of the Rite of Spring segment. And the animation for the Devil's Final Phase appears to be inspired by the lightings on Chernabog from Fantasia's Night on Bald Mountain segment.
- The screen when refusing to give the contracts to the Devil had an animated variant used in the E3 2017 trailer but was never used in the final version. This might have hinted, that the game was originally supposed to have animated cutscenes.
- The Devil's crystal ball attack is a close match and a possible reference to one of Crystal Man's attacks from Mega Man 5.
- At the end of the serpent transformation in Phase 1 of the Devil's boss fight, there is a lingering hit-box in the bottom left-hand corner of the screen. This means that if the player stays in the corner after the attack has ended, they can be hit by a seemingly invisible object and lose a life.
- The Devil, like King Dice, cannot be fought in Simple difficulty; only on Regular and Expert.
- However, using a hacked debug menu, you can fight him on simple. On this simple devil fight, you win after beating his first phase, where his skeleton will jump out of his skin and stay up off screen. The ending custscene will now play, which could be why his simple mode was removed.
- The Devil's art assets for Phase 2 is labeled as Phase 3, especially the art used for the underground transition intro, presumably meaning that an additional phase was planned to take place in the throne room, but got cut prior to the game's release.
- The quote for the final phase's death screen is a possible reference to M. Bison's victory screen from the console version of Street Fighter II.
- The achievement of defeating the Devil is called Swing You Sinners, a reference to the 1930 cartoon of the same name.
- The Devil is one of the two bosses that threaten to kill Cuphead during their introduction, the other being Djimmi The Great.
- The Devil is also the only boss that shows a dead Cuphead (and Mugman) in his death screen.
- The Devil's theme in the first phase is called Admission to Perdition and partly comprises parts from other bosses' themes such as High Seas Hi-Jinx!, Aviary Action!, Sugarland Shimmy, Junkyard Jive!, Fiery Frolic, Dramatic Fanatic, Floral Fury, Carnival Kerfuffle, Ruse Of An Ooze, Pyramid Peril, Botanic Panic!, Railroad Wrath and Clip Joint Calamity. It also has a part of Devil's henchman which is the bad ending theme. The song even winds down when it ends, much like Dramatic Fanatic. It also incorporates background solos reminiscent of the piano solos implemented in the intro music. The second phase theme called One Hell of a Time continues to have Junkyard Jive!, Botanic Panic!, Threatenin' Zeppelin and Fiery Frolic in the theme, it even has the announcement trailer theme in it. This may be meant to symbolize that Cuphead and Mugman aren't just fighting for themselves, but for the other debtors as well. Judging by the games files, this also would have been the theme for the demon bat if it were finished.
- The Devil seems to have retractable claws, seeing as they are missing in two of the cutscenes.
- He also oddly lacks a tail in game, yet has one in artworks.
- Two of Devil's trident attack was unused and replaced with the Devil's foot sprite, one has the Devil spawn three fireballs that bounce around and disappearing later, the other spawn two set of fireballs, each set has a stationary one with another orbit around it, each set will ram into the players and leave.
- In the unused Simple Mode, he would attack exactly like Regular Mode, the only difference seems to be he is knocked out in phase one. He will pull off his skin and leave it behind when the skeleton jumps up, not coming back down and create a hole to go down deeper. In later version like 1.1.3, the Simple Mode differences have been removed and would play like Regular Mode instead.