Holder of the Indigo Pacifier.

A member of the elite assassination team, the Varia. He has half of the Ring of Mist, thus battling Chrome in the gym of Namimori High. Though he almost defeats Chrome, the tables turns against him once Mukuro takes possession of Chrome's body. As a result, Mammon is defeated by Mukuro and loses the right to the Ring of Mist to Chrome. In the Future arc, he is said to be dead.

Before his battle, Reborn and Colonello have doubts of whether he is a Arcobaleno. He then reveals his sealed Pacifier, and claims that unlike his colleagues, he has been trying to break the curse. Due to extensive research, he created a chain that is able to conceal the power of the Arcobaleno pacifiers, as well as the Vongola Rings.

He has the special power to find a person's location by sneezing into a piece of paper (he carries a roll of paper with him); the spit or mucus that sticks to the paper shows a map leading to the desired person. He, like Mukuro, can create illusions.

His real name is Viper, and he has a black frog named Phantasma that lies on top of his head.

He represents the sin of Greed. Mammon is the false god of riches and avarice in Biblical literature.