Monkey D. Luffy, commonly known as "Straw Hat Luffy" or simply "Straw Hat", is the founder and captain of the Straw Hat Pirates. He pursues the legendary treasure of the late Gol D. Roger in order to become the new Pirate King and reach a further, untold dream (currently known to only his crew, family and closest friends). He believes that being the Pirate King means having the most freedom in the world.

Born on Dawn Island, Luffy is the son of Revolutionary leader Monkey D. Dragon and grandson of the Marine hero Monkey D. Garp and as such is a member of the Clan of D. Most of his childhood was shaped by Garp and Curly Dadan, under whose care he befriended and swore brotherhood to the late Portgas D. Ace and Sabo. However, he draws his greatest inspiration from the pirate Shanks, who (unwittingly) enabled him to eat the Devil Fruit that turned his body into rubber, sacrificed an arm to save his life, and gifted his signature straw hat as a symbol of their vow to reunite someday, after Luffy became a great pirate.

As a pirate, Luffy has actively opposed countless regional, national, and global powers, beginning with several established East Blue pirates and extending to the Marines, the Seven Warlords of the Sea, Cipher Pol, the World Nobles and Five Elders, and even the Four Emperors of the New World. Despite his young age and relatively short career, he has triumphed over a majority of these, successfully invading and indirectly causing the annihilation of Enies Lobby, escaping the impregnable Impel Down, enabling several key developments in the Summit War of Marineford, and defeating three Warlords and an Emperor in direct combat. At the same time, he carries a great penchant for attracting friends and allies; in addition to personally engaging every member of his crew, he has earned regard and gratitude among many nations, fellow pirates, the Revolutionary Army, and even several Marines.

Luffy has gained worldwide infamy through his accomplishments, heritage, and general recklessness, drawing many large bounties as well as the focused hostility of the World Government, Marine Headquarters, and Fleet Admiral Sakazuki in particular. Currently, he is recognized as a central member of the Worst Generation, the unwilling leader of the seven-crew Straw Hat Grand Fleet, and—in wake of defeating Kaidou during the Raid on Onigashima—one of the Four Emperors, with a bounty of Beli3,000,000,000. Since the awakening of the Gomu Gomu no Mi for the first time in centuries, Luffy has also been heralded as the second coming of Joy Boy, as well as the current incarnation of the Sun God, Nika.

Luffy is a young man who stands at 5'9" feet tall (5'8" pre-timeskip) with shaggy black hair with a small widow's peak, round black eyes, and a slim muscular build. Luffy's appearance is very similar to his grandfather Garp's as a young man, albeit a lot less muscular. He is renowned for his trademark yellow straw hat with a red hatband (from which he gets his epithet "Straw Hat Luffy"), which was lent to him when he was young by the legendary pirate captain, "Red-Haired" Shanks, who in turn received it from Gol D. Roger. Before the timeskip, his main outfit consisted of a red vest with three gold buttons, light blue denim shorts cut off just above his knees, and tan sandals. Luffy also has a scar with two stitches underneath his left eye, which he earned as a child by stabbing his face to show Shanks that he was tough enough to be a pirate. He was severely wounded by Akainu in the Summit War of Marineford, leaving a large X-shaped scar on his chest.

Before the Timeskip

Similar to most of his male crewmates, Luffy has the same outfit throughout most of the series. Luffy will often wear a different outfit to suit the climate of an island (such as a parka on Drum Island or desert robes in Arabasta) but will switch back to his trademark red vest and blue shorts after the adventures on that island are over. Despite this, he will wear his usual outfit in different colors and has been known to sport other miscellaneous items on his person from time to time like in Thriller Bark and Sabaody Archipelago. According to Eiichiro Oda in Volume 37 SBS, Luffy does not know how to dress stylishly, so sometimes he is advised on how to dress by more fashionable team members, Nami, Usopp, Sanji, and Robin.

During the Drum Island Arc, he wore two different parkas, the first being a burgundy parka with white fur on the cuffs, hood, and hem, and then a checkered, hooded parka with the colors white, orange, and bright yellow, which Nami wore in the beginning.

During the Arabasta Arc, he wore desert robes consisting of a dark red robe with three white rings decorated along both sleeves and a sky blue wrap over his head.

During the Skypiea Arc, he wore his vest open and additionally wore a black wristband around his left wrist with a white bangle over it. In Volume 37 SBS, Oda said that two members of his crew lent him accessories: a black wristband by Usopp and a white bracelet by Sanji.

During the Long Ring Long Land Arc, for the final match of the Davy Back Fight, Luffy wore an afro on his head, dark red shorts, and red bandages on his feet, getting an image of a blue flaming skull and crossbones painted on his chest as well.

During the Enies Lobby Arc, he wore black shorts with large cargo pockets.

During the Post-Enies Lobby Arc, Luffy wore a white T-shirt with the Galley-La Company emblem on it in red, red lines around the top, shoulders, and collar, and navy blue shorts.

During the Thriller Bark Arc, he wore an orange vest and reddish-brown shorts. After the battle against Moria in Thriller Bark, Luffy wore a dark decorated, jeweled armband around his left bicep, given to him by Nami. This armband was later revealed to be a map that leads to Captain John's lost treasure, which Buggy sought for some time; Luffy handed the armband over to Buggy in exchange for his services in navigating through Impel Down.

In a flashback to Thriller Bark during Episode 1136, this outfit is depicted with the addition of a purple sash and his shorts lacking a red tint.

During the Sabaody Archipelago Arc, in the manga, he wore a blue vest and red shorts (which can also be seen on the cover of Volume 52). In the anime, he wore black shorts instead of red.

During the Amazon Lily Arc, Luffy wore a deep sky blue vest with berry red shorts.

During the Impel Down Arc, Luffy wore his outfit from his stay on Amazon Lily until after his fight with Magellan, at which point he replaced his clothing with a yellow vest and vermillion shorts given to him by Inazuma. He would go on to wear this during the Marineford Arc.

During the Post-War Arc, Luffy had his red shorts from Marineford but with no vest, as well as bandages wrapped around almost his entire body due to the injuries he sustained. When he arrived on Rusukaina, he went back to his original red vest and light blue shorts, which is currently the last time he was seen wearing this outfit.

No matter where he is, Luffy wears his Straw Hat through absolutely everything, though at the start, the hat was prone to get knocked off his head easily, forcing Luffy to either put it aside or have someone hold onto it during fights. From the Arabasta Arc onward, he has gotten a string strap for it, which was sewn on by Nami, allowing the hat to hang on his back from his neck during fights, or stay more securely on his head for when he's in the air or upside-down.

During his return to Marineford to give a silent prayer, Luffy was briefly shown with four characters written on his right arm spelling 3D2Y, with the 3D crossed out to symbolize that the Straw Hat Pirates should meet up in 2 years (2Y) rather than the 3 days (3D) as planned after fleeing from Bartholomew Kuma.

During his journey, Luffy has used the power of his Devil Fruit in creative ways, many of which involve altering his body. The greatest example of his altered appearance is the creation of his Gear techniques which dramatically affect his entire body:

In Gear 2, Luffy pumps more blood throughout his whole body, causing his sweat to rapidly vaporize and making it appear that he is releasing steam. In the anime, his skin becomes tinted pink and shiny from the increased blood flow.

In Gear 3 form, Luffy blows a massive amount of air into his body, causing it to inflate and enlarge a specific part of his body to a size equivalent to that of a Giant. After the transformation wears off, his body temporarily shrinks to a child-sized form, with large hands and a vertically compressed head. The properties and appearance of this technique changed after the two-year timeskip.

After the Timeskip

After those two years, a few things have changed. He has grown slightly taller and is shown to be significantly more muscular due to his training. This can be seen in his slightly thicker neck, more pronounced deltoids, and a better-defined chest, which shows the X-shaped scar he received from then-Admiral Akainu covering most of it. His new "main" outfit retains his straw hat and light blue shorts, but instead of a vest, Luffy wears an open, 3/4-sleeved red cardigan with four gold buttons and a yellow sash tied around his waist with the end hanging from his left hip (somewhat reminiscent of Gol D. Roger's outfit).

Due to Luffy's increasing notoriety in addition to the increasing strength of his foes, after the timeskip he finds himself more often dressed in disguises to mask his identity, with varying levels of sophistication. Despite this, he still never loses his trademark straw hat and instead opts to at times cover it with other headwear.

During the Punk Hazard Arc, Luffy wore a long winter coat with red and white horizontal stripes, along with yellow earmuffs and dark red gloves, which he stole from one of Brownbeard's Centaur Patrol Unit. Just before leaving, he switched to a different coat that is all red with dark brown fur lining and a light brown belt, as well as brown gloves.

During the Dressrosa Arc, due to his need to hide his identity in Doflamingo's territory, Luffy wore an open, dark blue short-sleeved button-up shirt with a sunflower pattern, his standard light blue shorts and yellow sash, and a black bowler hat over his straw hat. He also wore a fake white beard and mustache. Upon entering the tournament for the Mera Mera no Mi in the Corrida Colosseum, he wore Viking-style armor with a red cape, complete with a sword and shield. Upon revision to meet the tournament's weight restriction, he got rid of most of the armor but kept the cape and helmet, along with his registration number '0556' and the word "Lucy" written on the back of his shirt, obscured by his cape. When he recovered after his battle against Doflamingo, Luffy wore a dark red tank top along with his standard shorts in brown (dark grey in the anime).

As he and the newly formed 'Sanji Retrieval Team' departed from Zou, he wore his standard outfit with light brown shorts.

During the Whole Cake Island Arc, Luffy wore an open, fancy white shirt with puffy sleeves, red trim, and an ornate gold pattern on the collar along with red shorts and his standard yellow sash. He also had a decorative scarf wrapped around his straw hat after landing at the Seducing Woods, though he appears to have lost it during his battle with Charlotte . These clothes were eventually torn to shreds after several battles, and he later dons a new outfit to meet with Capone Bege: a brick red blazer with matching shorts, a black dress shirt, and a pink cravat. He also fitted a black fedora with a white hatband to the top of his straw hat.

During his fight with Sanji, Luffy loses one of his top teeth after being struck by a Diable Jambe Joue Shot directly into his face. However, it grew back after he drank a bottle of milk.

During the Wano Country Arc, Luffy wore a red yukata with patchwork mon of a blue rounded sun on a cyan background and a yellow obi. He also had a topknot on top of his hair. He briefly had the Nidai Kitetsu he borrowed from Tenguyama Hitetsu. Before beginning the assault on Onigashima, Luffy received a set of samurai armor from Hitetsu. When helping Kin'emon and the others against Kaidou's fleet at sea, Luffy wore a long black coat, his usual red shirt, orange shorts, and a purple sash. He also briefly wore a Beasts Pirates disguise created by Kin'emon when infiltrating Onigashima, which consisted of fake red horns, black pauldrons with white lining, a black belt with white lining and the Beast Pirates jolly roger on the front, which is connected to the pauldrons by brown straps connecting to a silver ring, black leather pants, a red feather cape, orange gloves, and his regular sandals. During his celebration of the Raid's success, Luffy wears another red yukata, this one with a blue sash and yellow-and-white hexagonal patterns. In the following days, he wears a third red yukata with a purple ocean wave pattern and an orange sash. As he leaves Wano, he is seen wearing his Raid outfit, though with no coat and his orange shorts being swapped for golden yellow ones.

During the Egghead Arc, Luffy switches out his usual shirt for a long red coat with orange-yellow accents and the SSG logo, along with gloves, an earpiece, and a pair of red DOM Shoes. Underneath his coat, he is still wearing the same clothing he was wearing when he left Wano. During his fight with Kizaru, he discarded this attire, remaining in his yellow shorts, purple sash, and sandals.

During the Elbaph Arc, Luffy received a Viking-style outfit due to Road imprisoning him within his Land of Gods. The outfit consists of a long red fur cape, a pair of dark brown leather shorts underneath covered by a pteruges-like skirt of three light brown leather strips with three yellow dots on the front flap, as well as a wide yellow leather belt with a silver buckle and a black feather trim, a pair of long brown leather boots with light brown fur lining, a large black and gold Viking helmet with long curved horns, and finally a battle axe secured by an orange strap with a silver buckle that he carries around on his back. Beyond this, Luffy maintains a shirtless appearance with his Straw Hat casually hanging behind his ax and cape.

After the two-year timeskip, Luffy developed another two Gears, with one of them having its own sub-transformations, as well as significantly changing Gear 3:

During Luffy's two years of training, he further developed Gear 3 to have the air concentrated into his fist and a large sphere of air in his wrist, as opposed to throughout a whole limb as before. He also uses it in a variety of sizes, it does not shrink afterward, and it is almost always hardened with Armament Haki, giving it a shiny black appearance.

In Gear 4, Luffy's body proportions shift dramatically, specific to the exact form he is taking. In all forms, he gains dark rings around his eyes and a level of Armament Haki coating over at least his arms and legs that has crimson accents in addition to the typical black.

In the Boundman form, Luffy inflates himself, transforming his torso to be more spherical. He increases the size of his arms to match his torso and spreads Armament Haki coating over portions of his upper chest, creating the same type of swirls as those on the Gomu Gomu no Mi. In addition, his hair stands up on end, he gains black lining around his eyes, and his irises turn brown. In the process of inflating, Luffy also becomes taller and more muscular.

The details of the Tankman form's regular appearance are unknown, as Luffy has only used a variation called the "Manpuku Version." In the Manpuku Version of Tankman, Luffy's body goes through a similar yet exaggerated transformation to Boundman. In this form, his torso inflates significantly more than the rest of his body, while his arms only slightly inflate. The Armament Haki coating covers most of his body except for his chest, creating a flame-like pattern. He goes through a much more significant height increase, though he loses the muscular physique of Boundman to increase the roundness of his body.

In the Snakeman form, Luffy's body does not shift dramatically, remaining largely the same in terms of overall proportions. While some expansion still occurs, it's much less than in Boundman and Tankman, with the bulk of the transformation occurring in Luffy's much longer flame-like hair. Compared to the other forms, he has less Armament Haki spread on his arms, ending at his biceps. He also gains a trail of steam and fire that drapes over his shoulders.

In Gear 5, Luffy's hair, shirt, and shorts turn pure white and his sash or belt turns purple. His hair takes on the appearance of a flame, and his eyes glow with large red irises (pink in the anime). Like in Snakeman, he has a trail of gas draped over his shoulders, this time formed out of clouds.