Countess Malika Treszka was the alias of a leading Player. She had the form of a very beautiful woman with a cloud of dark hair and unusually blue eyes. She encountered the Sixth Doctor while attempting to arrange for Edward VIII to take the throne, but this plan was thwarted and resulted in the death of her associate, the Count, when she shot him by accident during a struggle. (PROSE: Players)
She later crossed paths with the Second Doctor many times as he struggled to anticipate or undo the damage she and the other Players were causing to the time stream by their efforts to alter the outcome of the Napoleonic Wars so that Napoleon would win, the Countess having determined that the collapse of Napoleon's expanded empire after his death would leave multiple smaller kingdoms that could be pitted against each other for the amusement of the Players. Thanks to the Doctor's efforts, the Players were forced to suspend their games "indefinitely". (PROSE: World Game)
Although she initially participated in the planned endgame to escalate the Cold War into open conflict, when she was confronted by the amnesic Eighth Doctor as she attempted to hynotise Joseph Stalin, the Doctor's pleas for her to leave humanity to its own destiny and his own shaken condition prompted her to accept his words and arrange for the deaths of her fellow Players, resulting in the endgame being declared void. (PROSE: Endgame)