The most distinctive thing about Koltopi is his haggard appearance. A thick and messy mane of hair flops down his face, obscuring everything except for an occasional glimpse of his eyeball.
Nen Ability: Gallery Fake - "Divine Left Hand, Demonic Right Hand"
When Koltopi touches an object with his left hand, his nen ability allows him to make an exact replica of that object with his right hand. He cannot replicate living things except as inanimate objects (making it likely that he created the fake corpses of his fellow members), and Koltopi is also unable to replicate another user's nen. The replicas that he creates vanish after 24 hours, regardless of their size. However, before their disappearance, Koltopi is able to track the movements of each and every copied object (providing that he can touch the originals).
In the Dark Continent Expedition arc, Chrollo is using his Gallery Fake ability during his fight with Hisoka, implying that Koltopi lent him this ability.
In chapter 357, he is apparently using a nearby bathroom while Shalnark discusses their plans to travel to the New Continent over the phone with Chrollo. Once Shalnark notes that Koltopi has been taking a long time doing so, it is revealed that Hisoka killed him when he emerges with Koltopi's severed head in hand.