Mephistopheles Arkadian

Mephistopheles Arkadian was a human arms dealer who also dealt in temporal artefacts. He was also in league with the Free Time movement, but stayed in impartial. Leela, K9 and Torvald, encountered him on Grybon, whilst searching for the any information about the free time movement and the threat of a Timonic Fusion Device. He lead them to Nepenthe, whilst himself taken to Gallifrey. He was the first person to call President Romana 'Imperiatrix'. (BFG: Weapon of Choice)

Later he invited Romana and Leela to the Calais Transcontinental Express to learn something about Miss Cecelia Pollard and Commander Torvald (BFG: A Blind Eye)

After the fall of the Matrix president Mathias invited him to remove Pandora's stockpile of weapons. He, however, was in league with Irving Braxiatel, to whom he had sold his Collection. When Braxitel's plan completed, he took the battle TARDIS bring the weapons, but was killed by Elbon who was affected by the Dogma Virus. (BFG: Panacea)