Black Man (Alien Bodies)

The Black Man was an agent of the Celestis with skin that was "a literal, almost-unbroken black". (PROSE: This Town Will Never Let Us Go) Homunculette speculated that the Man's skin was the result of extensive exposure to pollution and alien radiation. (PROSE: Alien Bodies) Valentine Bregman thought that the Man might have originated from West Africa. Bregman also thought the Man looked no older than 30, but felt that somehow that could not be true. (PROSE: This Town Will Never Let Us Go)

Despite the fact that he was a corpse, the Man emitted human lifesigns. (PROSE: Alien Bodies)

The Black Man wore clothing that looked both expensive and ragged. The Man's suit, jacket, shoes, top hat, and tie were all black, with the darkness broken up by three things: jewellery on his ears, an artificial red flower on his lapel, and incredibly bright white teeth. (PROSE: Alien Bodies, This Town Will Never Let Us Go)

When the Eighth Doctor visited Mictlan to confront the Celestis, the Black Man led a procession of "Mictlan's finest" to greet him. (PROSE: Alien Bodies)

Activity on Earth
The Black Man had a presence on Earth before it began being immensely affected by the War and Faction Paradox. Based in a British town, the Man was one of the only remnants of ancient witch-cult traditions; he was aware of Miss Ruth (the other local practitioner of ancient traditions), but they had never met.

In 2001, on the night before the beginning of the Ghost Point, the Black Man sold Red Uranium to Valentine Bregman. While negotiating the details of the transaction, the Man took Bregman on a ride in a black limousine. After Bregman agreed that he would use the Red Uranium outside of town, the Black Man briefly took the limousine into Mictlan. Bregman received half a critical mass of Red Uranium from the Black Man and the other half was delivered to his home. (PROSE: This Town Will Never Let Us Go)

In the 2160s, the Black Man sold weapons in the ruins of the House of Commons, which were empty following the 22nd century Dalek invasion. Many of his wares were salvaged from the Toy Box. In 2169, the Man sold Qixotl the Relic as part of a larger Celesti scheme. When Homunculette and Marie came to House of Commons searching for the Relic, the Black Man gave them an invitation to Qixotl's auction for the Relic in 2069. (PROSE: Alien Bodies)

Behind the scenes
The Black Man is briefly referenced in Interference - Book One without any new information about the character given: "home of a twenty-second-century arms dealer" is among the several functions the Houses of Parliament is listed as having served before its destruction.