Marco the Phoenix is the former 1st division commander of the Whitebeard Pirates. Once starting out as an apprentice on the crew, he had come to be Whitebeard's closest confidante and right-hand man. After his captain's death, Marco assumed leadership of the Whitebeard Pirates until the crew's disbandment following the Payback War. Since said war during the two-year timeskip, Marco works as a doctor at Whitebeard's home village, Sphinx. Marco is a tall, lean, muscular, blonde-haired man with a rather sleepy look on his face and some stubble around his chin. He wears an open purple jacket and a light blue sash adorned with an elaborate golden-yellow belt around his waist. He has dark gray knee-long pants and black sandals, and on his left leg he wears what appears to be some sort of straw decoration, in a similar fashion to Arlong. While his chest was bare in his initial appearance, in his subsequent appearances he has the cross and crescent moon mustache symbol that resembles a black silhouette of Whitebeard's Jolly Roger tattooed on it. Robin and Luffy believe that Marco's head looks like a pineapple.
Initially in the anime, Marco was given a generic crew member look of a black haired man with pale skin and different clothes. When he later became more formally recognized in the story, his appearance was changed to what is depicted in the manga, along with his light purple jacket, his black pants and his dark red tattoo. Later, starting with Opening 13 "One Day", he was given another color scheme. Once again his jacket was recolored in a much brighter purple, his pants were made dark blue, his tattoo blue and his skin a little brighter. Marco was a member of the Whitebeard Pirates twenty two years ago as well. Even at the age of 23, his appearance, for the most part, resembles his present self. As a kid, Marco's signature tuft of hair was more curly. He sported a vertically striped shirt, with black pants, and no shoes. As a teenager, his appearance was not much different. After the timeskip, while working as a doctor on Whitebeard's home island, Marco wears a light button-up shirt as well as a pair of eyeglasses. He also has more facial hair. During the raid on Onigashima, Marco wears his initial attire and retains his eyeglasses. Marco is generally calm and level-headed in the face of adversity or challenge; the only strong emotional moments he has shown so far were directly related to Whitebeard's health (after he was stabbed in the torso by his own subordinate Squard and after his death). When Ace and Whitebeard were killed, Marco and the rest of the Whitebeard Pirates were in tears.
In fact, seeing his captain, Whitebeard, get stabbed through the chest by a deceived Squard was enough for Marco to lose his usually unshakable cool-headedness that he immediately flew over to where they were to smash Squard's head against the Moby Dick's figurehead. He also demonstrates himself to be acute at detecting power, able to quickly notice the presence of Red-Haired Shanks' Haōshoku Haki before anyone else aboard the Moby Dick as well as the underlying potential of Monkey D. Luffy. He clearly cares for his crew as he warned them to stay back from Shanks' Haki. Having been a member of the Whitebeard Pirates for at least thirty years, Marco has an extremely high degree of experience with exposure and combat inside the treacherous New World. After Whitebeard's and Portgas D. Ace's deaths at Marineford, Marco took the position of commander of the Whitebeard Pirates, highlighting his level of intelligence and suitability in taking up a commanding position. He appears to be somewhat playful, pretending to be hurt from Admiral Kizaru's attack with obvious sarcasm, though he can also quickly become serious. Marco seems to appreciate raw talent, even if it comes from someone whom he had never met before (i.e. Luffy). Because of this, and based on the fact that Luffy intercepted Crocodile's attack on Whitebeard, Marco immediately took a liking to him. When he was an apprentice, he appeared to be a cheerful person. He was also encouraging as he cheered on Oden when he came close to passing Whitebeard's test to join the crew. He showed a playful side when he noticed Oden being close to Toki. Marco ate from the Tori Tori no Mi, Model: Phoenix, a Mythical Zoan-type (thus rarer-than-Logia) Devil Fruit that allows him to transform into a large, blue-flamed phoenix, the source of his nickname "Marco the Phoenix". Apart from enjoying a general heightening of his physical parameters, as an avian Zoan type, Marco can take flight in both his full phoenix and hybrid forms, and his control over the latter form is such that he can isolate it to specific body parts, e.g. transforming just his arms into wings to fly, and his feet into bird legs/slashing talons as necessary. The greatest aspect of Marco's ability is that he can freely conjure forth his "Blue Flames of Resurrection" from any part of his body (even without actually shapeshifting) and, by enveloping himself in those flames, rapidly self-regenerate from almost any physical damage he receives like a phoenix being reborn. It is noted, or at least implied, that no matter what injury Marco is dealt, he can recover by flame (even injuries suffered while his powers are being sealed). Such immense power of recovery, coupled with his seeming increase in durability when transformed, allows Marco to ward off extremely potent attacks with little issue, like Kizaru's barrage of light beams or even Akainu's magma punch, which had taken the life of Ace. In addition, Marco can apply his flames to others in order to mend them like himself (even many individuals at once), though still being more limited in that capacity.
