Luffy is renowned for wearing his trademark Straw Hat (from which he gets his nickname 'Straw Hat Luffy') which was given to him when he was young by the legendary pirate captain Red-Haired Shanks. His outfit somewhat mimics Shanks' own outfit in that he wears short trousers (although his are much shorter then Shanks') and sandals. Luffy also wears a red vest and has a scar underneath his left eye and short black hair.
Luffy, for some reason, has the same outfit over most of the series, as opposed to the rest of the crew. Luffy may wear a different outfit to suit the climate of an island (like a winter coat on Drum Island or desert robes in Alabasta), but will switch back to his trademark vest and shorts after the adventures on that island are over. Notably, in Enies Lobby he wears black shorts and on the Thriller Bark Island he wears an orange vest and red shorts. He does, however, no matter where he is, wear his straw hat through absolutely everything. Eiichiro Oda has mentioned that Luffy mostly resembles a monkey (he sometimes even makes a monkey face) . According to Oda, Luffy is represented by the color red, and smells like meat.
As of Thriller bark, he has been wearing a glass armband that he found in the loot stashed on their ship.
At first glance, Luffy does not appear to be very intelligent; his apparent lack of intelligence is the source of his brave attitude towards life.Luffy can easily be amazed by the simplest things, such as hermit crabs, and can be confused by concepts such as that by digging a hole right next to another he may be unintentionally filling the other hole. Because he views the world in a straightforward and simple manner, he occasionally is the only person who can see past events that have taken place and realize the true goal, yet at other times he can fall into the simplest of traps. He is, however, a genius when it comes to fighting, such as when he figured out how to defeat Crocodile's Devil Fruit power, how to use Soru, and developed an effective counter to Enel's "Mantra" ability. He also appears to be intelligent enough to at least understand fundamental concepts, such as rubber being a natural insulator, which might be why he did not bother ducking out of the way of Eneru's lightning attacks as it would have been pointless to do so since he is immune to such attacks. He also is heavily influenced by any form of hypnotism and doesn't have the sense to turn away, such as Jango's hypnotism powers or Miss Goldenweek's Colours trap. Regardless, while easily noticeable as the least strategic member of his own crew, due to his tendency as the type to simply just barge in head-first into battle (often without a battle plan whatsoever), Luffy is a highly adaptive combatant; constantly coming up with ways to keep ahead of his foes, either by taking advantage of his own strength and Devil Fruit powers or utilizing the opponent's own strengths against them causing even warriors long considered unbeatable to have trouble keeping up, he does have a habit of holding a grudge even in dire situations (such as calling Franky a "bastard" in the middle of his fight with Rob Lucci causing Franky to retort "Now's not the time to be mad at me"). When drawing him, Oda has said he tries to make Luffy very straightforward about what he wants to be and how he feels.
Much like his idol, Shanks, Luffy is the kind of benevolent pirate captain who doesn't seek to actively harm others unless they give him and his crew (or anyone he cares about) a very good reason to. As a person with the initial letter D, Luffy shares the common trait of not fearing of death. He will often state that if he reaches his goal, that's fine, but if he dies on the way, that's fine too. He even smiled when he was nearly executed by Buggy the Clown in Loguetown.. Though he did had a look of shock and surprise in his eyes before this happened when Sanji and Zoro tried to rescue him. Luffy seems to have an unstoppable appetite which is another common "D" trait, as well as a strong belief in dreams.Like other D's so far, he also is a glutton, despite his skinny appearance: he especially loves meat and can eat a fish whole - bones included , because of this, a running gag is Luffy constantly stealing other peoples' food with his rubber arms, causing them to yell at him and sometimes hit him. Another running gag is his habit of being amazed of various abilities of villains often yelling out "AMAZING" with stars in his eyes and around his head. He also constantly insults his opponents by giving them degrading nicknames (such as calling Don Achino a "Naked Balloon" and calling Gecko Moria a "leek"). Luffy also seems to have a slight obsession when it comes to outfitting himself with full-body armors, and has a knack of wearing himself one whenver he gets the chance, but every armor that he manages to find and outfit himself with usually ends up destroyed either in a battle or by some other comedic scenario
Luffy never kills any of the villains (no matter how cold-hearted they are); instead, he frequently sends the villain flying, knocking them out or until the point that they are almost near death, which results in some of the villains searching for revenge, such as Buggy the Clown. Oda explains that it's not a question of morality so much as a matter of punishing the villains for their crimes - he feels that killing the villains lets them off too lightly, whereas he considers letting them live to see their dreams be ruined a far more fitting punishment. Another dominant trait of Luffy is his humble nature: he doesn't brag about the powerful foes he's defeated in the past, though he's not above about claiming that no one has ever beaten him in the past, - which is not true, having been defeated at several times times, at least once by Ace, twice by Crocodile and once by Aokiji in the past. Despite this, he remains humble despite having done outrageous acts like defeating Shichibukai-level pirates and issuing the order to burn down the World Government Flag back at Enies Lobby. When Franky pointed this out, Luffy only replied that it was nothing to get worked up over, for he and his crew were only there to take back a nakama who was taken from them. Over the series Luffy has become more mature and levelheaded, though he only shows this part of his personality when he and his friends are in dire situations or someone insults him, calling people like him and their beliefs foolish; other than that he still acts the same as he was at the start of the series.
Luffy calls every mixed-appearance creature he finds by whichever creature is its secondary (non-dominant) part. On Gaimon's island, the dog/chicken was referred to as a chicken when it was mostly a dog, the snake/rabbit a rabbit even though it was mostly snake and the pig/lion a lion even though it was mostly pig. This becomes a running gag: later when he meets Bananawani, he calls them bananas with crocodiles attached to them.
Easily the strongest member of the Straw Hat Pirates, Monkey D. Luffy has extraordinarily inhuman strength, and can move in superhuman speeds, eventually catching up to even the speed of CP9 agents. Other Straw Hat members who can even rival Luffy's strength (without him accessing other Gears) are Zoro and Sanji, appropriately dubbed "The Monster Trio" of the group. His sheer physical strength and dexterity is a result of his grandfather's unorthodox training methods and he claimed he had a punch as powerful as a pistol even at seven years of age. [25] However, it should be also noted that all of the known members of Luffy's family have superhuman strength. His strength is only exceeded by his enormous willpower, as demonstrated on several occasions throughout the series, most noted of all in the Thriller Bark Arc when he manages to take in 100 shadows without passing out. [26] Unlike Zoro or Sanji, Luffy's fighting style is freestyle and improvised; it follows no particular code of honor, and so if necessary he will attack women or animals, hit below the belt, attack even if enemies have their backs turned on him, use enemies as human shields or even bite his opponents. While fighting, Luffy can also think on the spot, and come up with creative counterattacks against his enemies, and even learn and improve while he's fighting. Luffy has also begun to awaken a similar "Spirit Energy" ability similar to one used by his hero Shanks. This power first manifested itself when Luffy calmed down Motobaro, Duval's bison steed.
Luffy also has the mysterious and uncanny ability to, while completely asleep, eat as if he were awake, even able to know when more food has been placed on the table. [27] This is probably purely based on muscle memory since all Luffy does best is fighting and eating. Another running gag in the series is about Luffy is his inability to draw. In the start of the Arlong Arc, imagining how a mermaid would be Luffy drew a fish with tentacle-like paws and an anthropomorphic fish with arms, legs and hair. Before the Straw Hats arrived at Water Seven, Luffy drew a childish picture of what he wanted the future shipwright to look like. This inability also extends to Jolly Rogers: the first Jolly Roger of the Straw Hat Pirates was a bad drawing designed by Luffy himself (he later used a similarly bad drawn version of his Jolly Roger as a promise marker on the face of Laboon) while also drawing a bad version of Foxy's flag after taking it from him in the Davy Back Fight arc. As the strongest of the Straw Hat Pirates, he always fights the most powerful enemy at the time, Franky himself notes that if Luffy wasn't holding off Lucci, he wasn't sure if anyone from the crew would make it past him.
Luffy has gained extraordinary stretching powers from eating the Gomu Gomu no Mi, which is one of the rare and legendary Devil Fruits. After consuming the Gomu Gomu no Mi, Luffy's body becomes like rubber, giving him the ability to stretch long distances. Having trained hard for ten years, Luffy is able to supplement his stretching powers with immense strength, agility, and creativity in combat. His fighting style is largely improvised, and heavily reliant on his Devil Fruit.
Luffy uses his stretching power in ingenious ways. He is able to use the malleable stretchiness of his limbs to gain tremendous velocity and hit enemies with devastating impact. His rubber body is also virtually immune to blunt objects such as bullets (in One Piece, bullets are still round pellets), punches and electricity, either reflecting off his body harmlessly or being absorbed into him. It's even become a running gag that people find out the hard way Luffy is made of rubber when they shoot at him, only to have the bullets bounce right back. However, he is still normally susceptible to sharp objects such as swords and knives. He can not only use his ability to increase the range and strength of his attacks, but he can also use it to restrain and even control foes like puppets.
Like all Devil Fruit users, Luffy cannot swim (although he could not swim even before he ate the Devil Fruit). Even though blunt objects do little damage to him, sharp blades or points can harm him and blunt attacks can also hurt Luffy if enough force is put into it, as well as nonphysical attacks like flames, explosions, freezing and dehydration.