Marowak is a bipedal Pokémon with light brown skin and a cream-colored underside. Two small claws, one on each hand, serve as its thumbs, and one large nail on each foot make up its toes. It has a short tail with a small spike near the tip. Marowak's head is composed of the skull it once wore as a mask. It can no longer remove the skull, which has become part of its body. The skull has two pointed spikes on the back similar to ears and tiny nostrils on the tip of the snout. Marowak's triangular, brown eyes are also located in the skull. Marowak is well known for ferocity with its bone club, which it is said to collect from a hidden graveyard. Marowak and its pre-evolved form, Cubone, are the only known Pokémon that can learn Bone Club and Bonemerang, the only Pokémon capable of using the Thick Club item, and once claimed Bone Rush as another signature move.
Upon evolution, Marowak has overcome the grief of its mother's passing. Now ferocious and violent, Marowak is an adept combatant that uses the bone it carries as a weapon and a boomerang. Having evolved, it seeks vengeance on its natural enemy Mandibuzz, which prey on Cubone because of its naturally weak and timid demeanor. Marowak has also been recorded pounding on boulders with the bone club it carries in order to tap out messages to others. It lives in mountains to test its skills.
In the Alolaregion, Marowak was faced with an abundance of its natural enemies, Grass-type Pokémon. This harsh environment led it to bond closely with its friends, which is said to have created a sort of sixth sense and caused it to take a new form. Alolan Marowak's body is black and it has pale gray eyes. There is a dark, flamelike mark on its skull between the eyes. Compared to regular Marowak's squatter, thicker body, Alolan Marowak is relatively thin. White markings resembling shoulder blades, vertebrae, and hip bones are visible on its back. The bone Alolan Marowak uses is longer than the one regular Marowak uses. It customarily mourns its companions by burying them and dance in mourning.
Alolan Marowak rubs the bone it wields against its forehead to light the ends in a green flame, and then twirls the flaming bone. It specializes in an attack where it releases a weak ball of flame from its bone that will relentlessly pursue its foe. Alolans would fear it for a conjurer, due to its rarity and the fearful sight of it dancing with its bone. The dance is also used as a way of mourning for its lost allies. Once its flames have spread onto an opponent, they are impossible to put out with water. The flames are known to cause both mental and physical pain. Alongside retaining the ability to learn Bone Club and Bonemerang and use the Thick Club, Alolan Marowak is the only known Pokémon that can learn Shadow Bone.
In Bad to the Bone, a Marowak belonged to Otoshi, who had recently got his GymBadges stolen by Team Rocket. Marowak left Otoshi because it felt that if he lost his Badges, he lost the respect Marowak had for him. By the end of the episode, Marowak came back to help by battling Team Rocket to get his Badges back.
According to some of Marowak's Generation II and IV Pokédex entries, somewhere exists a legendary Marowak graveyard. This is a reference to the elephants' graveyard of modern myth.
Alolan Marowak is the only dual-type Pokémon that shares no types with its pre-evolution.
Though Alolan Marowak shares the AbilityRock Head with Cubone, a Cubone with Rock Head cannot evolve into an Alolan Marowak with the same Ability, as Rock Head is Cubone's first Ability and Alolan Marowak's Hidden Ability.
Alolan Marowak's design may draw inspiration from a fire dancer holding a fire staff or a fire knife, a Samoan traditional dance implement. Alolan Marowak may have also drawn inspiration from the Polynesian concept of mana, a spiritual essence that exists in all objects and people. It also allows people to imbue their "spirit" into other people and objects for protection or vengeance. In addition, Alolan Marowak may have been inspired by Nightmarchers, ghosts from Hawaiian mythology that march at night, are feared by the living, and traditionally are known for carrying torches as they march.