Caesar Clown (in Japanese: シーザー・クラウン Shīzā Kuraun), also referred to as "Master" (in Japanese: マスターMasutā) by his underlings, is a former colleague of Vegapunk and the primary antagonist of the Punk Hazard Arc in the anime and manga, One Piece. Caesar is the leading expert on mass-murder weapons and is a mad scientist with a bounty of 300,000,000 beri on his head.
Caesar Clown is perhaps one of the most sadistic characters in One Piece as he enjoys seeing people suffer. He pretty much cares for himself than anyone else and has shown to be very deceitful and manipulative such as when he rescued a crew of pirates and helped them but instead used them for his cruel experiments. Caesar also has no remorse for his actions and will sacrifice children for his experiments with no care for them. When it came to Brownbeard and his crew, Caesar sees them as "guinea pigs" who are scum of the Earth that people would not care for if they died; this is an example of how he saw them as tools and just how vile he truly is. He does not care for the safety of anyone as he will even allow Shinokuni to kill off one of his comrades, Vergo, if it means that the Marines and the Straw Hats die from it as well. Caesar is very prideful as being one of the best minds in science and sees himself as a better scientist than Vegapunk, his rival, and has shown to be incredibly jealous of the latter. Despite his overall selfish and psychopathic personality, Caesar praises Donquixote Doflamingo and respects him because of the protection the latter gives him to do his experiments.
At times, Caesar can be dramatic and silly as he overacted over having his heart crushed even though it was not his real heart. Like Spandam, Caesar will run away from a problem that he started and will try to talk himself out of a situation. And like the latter, he has a temper.
Caesar has the Gasu Gasu no Mi which is a logia type devil fruit that grants him the ability to turn into gas. With this ability, he can become intangible but he can still be attacked by anyone using Haki. Caesar's use of manipulating gas can also be used to even suck the oxygen out of the air to suffocate his opponents. Caesar can shoot laser beams from his mouth by manipulating the gas which can cause an explosion. He can also make the gas around him become poisonous and flammable in his battles. Before he got cuffed by seastones by Ussop, Caesar was shown to have his devil fruit active at all times. When Caesar merged with Shinokuni, he was able to petrify targets near him and have control over the gas at a longer distance.
Besides his devil fruit abilities, Caesar also carries around a gun and he is also good at using a sword in battle. Caesar also uses castenets which he calls "Gastenets" which he uses to create giant explosions by manipulating the gas in the air. He is also a very intelligent scientist as he was the capable of making artificial devil fruits, weapons (mostly weapons of mass destruction), and conducting other experiments. Caesar also posses superhuman strength as he was able to swing his sword at an immense speed while fighting Luffy and withstanding powerful blows to the face by the pirate.
Caesar used to work for the Marines on Punk Hazard with his rival Vegapunk. One day, Caesar was annoyed at Vegapunk's appearance. Caesar decided to blow up the island killing many people, destroying the vegetation and wildlife on the island, and becoming a criminal of the World Government. Caesar remained on the island for some time where he helped out the people who drifted ashore to the island but in reality he was manipulating them. At some point, Caesar began to work for Doflamingo where he created artificial devil fruits to empower Kaido's army.
During the timeskip, he was confronted by Law who wanted to join his team. Caesar decided that Law should give Monet his heart for her own heart to prove his loyalty and credibility to their group.
Punk Hazard Arc
Caesar first appeared when the remaining Straw Hats broke out of their cell. He was interested in Franky because of how his weapon system that came from Vegapunk. Caesar was surprised to know that the G-5 Marines were on the island and was shock to hear that the Marines saw the kidnapped children. He was also surprised to learn that the Straw Hat Pirates' were present on the island. Caesar then blames Law for allowing the Marines to see the children. He later contacts Joker who gave him permission to kill off all the intruders on the island. He later killed off a centaur troop member after he told him that Brownbeard got captured by the Straw Hats to test out his experiments that he deemed was anything but a failure. He told Monet that he was the best scientist out there and all his experiments were not a failure. Law later returned to give Caesar, Smoker's heart and revealed to Law that he sent the Yeti Cool Brothers to capture Franky and kill the Straw Hats including Brownbeard. At first, Caesar was skeptical about Law's loyalty to his group because of his relationship with Monkey D. Luffy in the past. He decides it was safe with Law and revealed to him that he was drugging the children to keep them on the island much to Law's disgust. Caesar later released his pet, Smiley, to unleash chaos on the island and went outside to see it in progress. Once outside, he was ambused by Luffy (who was going to capture him) and got into a fight with him where he defeated him, the Straw Hats that was with him, and the Marines.
Caesar later went to the hiding spot where Nami and Ussop were at and defeated them, got the children and mocked a beatened Brownbeard. Back at the laboratory, Caesar confronted Law on his betrayal and the captured Straw Hats and Marines and proceed to torture Law by crushing his heart (that Vergo gave him) because he insulted him. He then turned his attention to Shinokuni (the rising poisonous gas) and then broadcast it to the people on the black market who wanted it. He later released the captured Straw Hats, Law, Smoker, and Tashigi outside to allow them to die by Shinokuni. He attempted to kill off as many people on the island by trying to expose them to Shinokuni. After some time pass, Caesar was confronted by Luffy again, where he got into another fight but he escaped and left Monet to deal with the pirate. Caesar was later contacted by Doflamingo and was ordered to return to Dressrosa with Monet and Vergo because of what was going down on the island. He was seen with his subordinates and he ordered them to allow Shinokuni to flow through the building to kill off the enemy. Brownbeard later appeared and tries to warn his comrades about Caesar. However, Caesar manipulated the situation to make Brownbeard look like a traitor to his comrades and continued to mock him by whispering to him. When Caesar was about to land a finishing blow on Brownbeard he caught off gaurd by a Haki-infused punch to the face by an infuriated Luffy.
Caesar tries to explain to Luffy that if anything happens to him then he will have to face bigger threats in the New World like Doflamingo and Kaido. Luffy ignored his words and punched Caesar in the face again. After Law leveled the island with his attack, Caesar viciously ordered his subordinates to release Shinokuni into the room to power him up at the cost of his teammates safety. When Caesar fused with Shinokuni he tried to kill off everyone in the room but was easily defeated by Luffy with a Haki infused attack and was sent reeling outside the building. After regaining consciousness from the attack and seeing Baby 5 and Buffalo fight Franky, Caesar attempted to kill Smoker by stabbing him in the heart but unknowingly to him he killed Monet instead. Later after seeing the Straw Hats, Marines, and children outside of the building unharmed, he tried to go Dressrosa on his own but was captured by Ussop and Nami and was cuffed with seastone. Caesar was then interrogated by the Marines on how to undo the effects of Shinokuni. After the Straw Hat crew treated the children for their poisoning, Law incapacitates Baby 5 and Buffalo and Caesar was captured by them in their attempt to dethrone Doflamingo from the position as a Shichibukai.
On the Sunny Ship, Law allowed Caesar to talk to Doflamingo to prove his safety. Once everyone arrived to Dressrosa, Caesar was put into a group with Law, Robin, and Ussop where they decided to head to Green Bit to meet Doflamingo. When they were in town, they had to put on a disguise and then wait for the time to meet Doflamingo at the bridge. When they were battling the Fighting Fish on the bridge to Green Bit, it was revealed that Law took Caesar's heart. After Robin and Ussop separated from the group, Doflamingo and Admiral Fujitora appeared. Doflamingo revealed to them that he was still a Shichibukai much to Caesar's delight. As the fight between the Admiral and Shichibukai commenced, Caesar and the Marines ran into the forest to avoid the dangerous clash. After the fight was over and Law lost, Caesar wanted to know where his heart was. Law then escaped from a distracted Fujitora and grabbed Caesar to return him to the Sunny ship where the Straw Hats (Sanji, Brooks, Nami, Chopper, and Momonosuke) were because Doflamingo did not honor his deal. Law decided to give Caesar his heart back and revealed that he had it inside himself for most of the time.
Now deciding to sail away from Dressrosa to escape from Doflamingo, the Straw Hats were planning to sail to the next island, Zou, but Big Mom's ship appeared and her subordinates wanted to capture Caesar. Caesar was frightened because he used to embezzle from Big Mom and did not want to suffer her wrath. He begged the Straw Hat pirates to save him which they reluctantly agreed to do only because it is apart of their overall plan to take down Kaido.
After a day have past, the Straw Hats manage to avoid Big Mom's ship and made it to Zou. When they arrived on Zou, Caesar was emphatic to see the destructive effects of his weapon Koro that Jack used on the minks. He warned the Straw Hats that it is not in the best interests to help the minks because of the legends he heard about them in regards to how they despise humans. To his reluctance, he was forced by the Straw Hats to disperse the Koro gas that Jack had used and to help out the civilians who had been attacked.
After some time passes, Big Mom's men made it onto the island to look for the Straw Hats and Caesar. Caesar was shocked to see them on the island. He wanted to collaborate with Sanji to kill them but the latter ignored him and decide to meet them face-to-face. While meeting with them, Pekoms was glad to see that his family and friends were saved by the Straw Hats and demanded only for Caesar to come with him. Capone Bege did not like how Pekoms was handling the situation by letting the Straw Hats go and decides to knock him out with his cannon. As Capone's men began to corner the Straw Hats, the pirate threatened Caesar to come down or else he will get shot by seastone bullets from his men. Caesar got down from the tree but Bege lied saying that he did not have seastone bullets but a seastone spear.
The Straw Hats and Caesar were taken into Capone Bege's body where Sanji got an invitation to a tea party wedding from Big Mom where he will be the groom. Sanji reluctantly agreed to go with them to the wedding and he managed to push his comrades out of Capone's body. Caesar was shocked that he was left behind. Sanji then stole a gun from one of Capone's men and held Caesar as a hostage so that it could prevent his men from chasing after his friends. Capone decides to listen to Sanji's request and they left Zou.
Whole Cake Island Arc
On the way to Whole Cake Island, Caesar was locked away in a cage in Sanji's room. He was angry and wanted to be liberated but Vito told him that he was going to be locked up in there anyways. After arriving on the island, Caesar was immediately taken to Big Mom where they discussed the progress of his experiment on gigantification. Caesar lied and said that the experiment was going well but it was interrupted by Luffy and Law. To his shock and dismay, Big Mom revealed that she had a replica of his laboratory that was on Punk Hazard. She told him that he had two weeks to complete the gigantification experiment or he will die. He was supervised by Charlotte Perospero, Big Mom's first son, who kept an eye on him. Caesar was overwhelm because he knows that the gigantification experiment would be impossible to complete within two weeks and that it has never been completed successfully.
Later on, Capone Bege switched his role with Perospero and told Caesar that he would be free of his captivity if he decides to help him in his plan to assassinate Big Mom. Caesar was angry as his heart now went from Perospero to Capone and that he was under the servitude of Capone. He later attend a meeting with the Fire Tank Pirates and the Sanji Retrieval Team where they went over the plan to assassinate Big Mom, save the Vinsmoke Family, and escape from Whole Cake Island. Caesar reveals that he has a weapon called the KX Launchers that would be used to kill Big Mom by poisoning her. After the meeting, the alliance prepared for the wedding in advance. Before the wedding began, Capone asked Caesar if the mirror was prepared for the plan. Capone reminded Caesar if anything happened to the mirror, then he will crush his heart. Caesar assured him that nothing will happen.
As the wedding begins, Caesar appeared in the Mirror world with the alliance. As Luffy's clones began wreaking havoc in the ceremony, Caesar was left in the mirror world with Brulee. He later traveled with Brulee out of the mirror world to observe the plan unfold in the wedding ceremony. He noticed that the plan is well but that Big Mom had no screamed yet. When she screamed and the assassination plan failed, Caesar appeared with the mirror for the escape plan. However Big Mom's loud scream shatters the mirror leaving them trapped there. The group and the Vinsmoke Family made their way into Capone Bege's Big Father castle body for protection against the Big Mom Pirates. While the group think about a plan to escape from the wedding venue, Capone decides to have his body turned back to normal and have Caesar fly them out of the wedding venue with protection from the Vinsmoke Family. When the castle is destroyed by the tamatebako box, Caesar and the Straw Hats made their way to the woods away from the disaster in the town. Bege gave Ceasar his heart back and then left from everyone.
- Caesar was the title for the Roman emperors, derived from the cognomen of Julius Caesar.
- Like Magellan, Caesar's sinister face, wild hair and horns make him resemble a stereotypical image of a demon; particularly Baphomet, a pagan deity-turned-devil most commonly depicted as a humanoid goat.
- In his first appearances his coat did not show "GAS" written twice on the front as it does in Chapter 666 and Chapter 671.
- He is also, so far, the only Devil Fruit user who seems to keep his Logia Devil Fruit active all the time, giving him his gaseous appearance.
- He is the second Devil Fruit user to alter the properties of his own fruit's power using artificial chemicals, the first being Tony Tony Chopper with the Rumble Balls.
- Caesar's Japanese Voice Actor, Ryūsei Nakao is largely known from his previous roles in other Anime such as Mayuri Kurotsuchi from Bleach and in One Piece: Strong World as Indigo. Oddly enough, all three individuals have similar behavior and position (crazy, sadistic scientists). Interestingly both Caesar and Mayuri are both forced to work alongside the heroes.
- In Chapter 663, his name is spelled as "Caesar Clown" which takes place of the hiragana, as seen Smoker's monologue. However, in Volume 68's character introduction, it is spelled as "Caesar Crown".