PeacemakerJames SwallowDoctor Who: New Series Adventures, book 21

Characters in Peacemaker

5 characters, main characters first.

Main characters

Martha Jones
Also in Winner Takes All, The Story Of Martha, Made of Steel
The Doctor (Doctor Who)
The travelling Time Lord at the centre of the series, who moves through time and space in the TARDIS and changes appearance on regenerating.
Also in Winner Takes All, The Stealers of Dreams, Wooden Heart, Doctor Who, Wetworld, The Pirate Loop, The Story Of Martha, Made of Steel, Dr. Who

Antagonists

Shadowy outriders
Intergalactic mercenaries

Supporting characters

Snake-oil salesman