Nicolaus Copernicus

Nicolaus Copernicus (1473 - 1543) (Italian: Niccolò Copernico, Polish: Mikołaj Kopernik), was a Polish astronomer, mathematician and priest. He was the first person to present a correct model of Heliocentrism.

Rome
In 1500, Copernicus visited the Vatican, where he was introduced to the Templar Order. Upon joining them, he was later told that they wanted him to keep his discoveries secret. A day afterwards, though, he enlightened the public on science and mathematics, saying that he was unable to keep his findings to himself. As soon as the Borgia, the leading house in the Templar Order, heard of this, they sent their guards to kill Copernicus. Ezio Auditore da Firenze, an Assassin, watched the scene unfold and came to Copernicus' rescue.

Copernicus admitted his affiliations to the Templars to Ezio, though the latter was willing to help Copernicus reach a safe location. Upon arriving there, Copernicus asked Ezio to deliver some documents to his fellow scholars, which would inform them of the danger they were in. Ezio returned some time later, and by then, Copernicus had concluded that the Master of the Sacred Palace was most likely behind the plot to kill him. Ezio sought out the Master of the Sacred Palace and found that there were five executioners walking around Rome. Ezio rushed to take these executioners down and returned to Copernicus with the confirmation that it was indeed the Master of the Sacred Palace who was plotting to have him killed.

Copernicus, however, was persistent to go out in the open to study a lunar eclipse. The Master of the Sacred Palace seized this opportunity and sent an assassin to kill him. Ezio followed and killed the Master of the Sacred Palace before returning to Copernicus, with whom he took down the assassin and several other guards. The pair then went their separate ways, with Copernicus staying behind to study the eclipse.

Trivia

 * Copernicus is also briefly mentioned in Assassin's Creed: Project Legacy.