Giuliano della Rovere is one of the main antagonists in the Showtime series The Borgias. He is the bitter rival of Rodrigo Borgia.
As the series began Pope Innocent VIII was dying. He regretfully stated that the church is in very bad shape and asked who would clean up the church, a question that seemed to be pointed at della Rovere and Borgia.
During the conclave della Rovere informed Borgia that he thought he was a corrupt, immoral man, and that della Rovere would oppose him. Borgia meanwhile was busy garnering support, first by having the Cardinals favorite meals delivered to them, and then by sending precious metals to their castles. Borgia then put himself over the top by promising the Vice-Chancellorship of the church to Ascaino Sforza. Upon Borgia's winning the election della Rovere angrily accused Borgia of using simony to gain the Papal office, however the election was allowed to stand and Boriga was introduced to Rome as Pope Alexander VI.
Soon after the election of Alexander the elderly and highly respected Cardinal Orsini was murdered by Micheletto Corella, an act that della Rovere was accused of perpetrating. della Rovere soon departed for France, where he hoped to ally with French King Charles VIII and have him depose Alexander so he could be named Pope.
However Alexander was able to outmanuever della Rovere and convince Charles VIII to leave Rome alone. After losing support from the French King della Rovere went in to hiding as a parish priest serving the nuns of the Order of St. Agnes and the surrounding commune. He was very nearly assassinated by Cesare Borgia and Corella, who had bribed an altar boy to poison the communion wine della Rovere was to use at Mass with cantarella. While the cantarella did not kill della Rovere, it left him seriously ill for several days. Laying in bed, unable to speak della Rovere received a visit from Cesare, who warned him there was no where he could hide that the Borgias would not be able to reach him. The experience left della Rovere shaken and unwilling to eat or drink anything except rain water for fear of further poisonings.
To ensure the safety of his food, della Rovere acquired a capuchin monkey to eat or drink a portion of anything presented to della Rovere. Asked if the monkey had a name, della Rovere responded that the monkey's name was Julius, foreshadowing the name he himself would one day take as Pope.
Working with monks who felt as he did about Alexander, della Rovere managed to insert an agent into the Vatican as a food taster. Given poison by della Rovere, this agent was told to wait until the time was right. The agent soon saw his chance to poison Borgia and administered the poison to Alexander and his son Cesare.
When Alexander fell victim to the poisoning attempt, della Rovere thought that the hour of Alexander's death was finally at hand and rushed back to Rome. The Pope however made a full recovery thanks to the assistance of his daughter Lucrezia. della Rovere was arrested by Cesare Borgia, who intended to execute him for the crime. della Rovere slipped away by arranging to be carted away in a cart loaded down with corpses.
Cardinal della Rovere's ultimate fate is not known in the course of the series due to the abrupt cancellation of The Borgias. However in the Borgia Apocalypse it is mentioned that after the events of the series della Rovere would himself be elected as Pope, taking the name Julius II.