* Peter the Great (ruled 1682-1725) was the first Tsar of the Russian Empire, who dramatically modernized and expanded Russia. He died in 1725.
* Catherine the Great (ruled 1762-1796) was the Empress of Russia. She was not a direct descendant of Peter the Great, but came to power through a complex chain of events.
Here's how they are related:
* Catherine the Great was married to Peter III. Peter III was the grandson of Peter the Great's daughter, Anna. This made him Peter the Great's great-grandson.
* Catherine seized the throne in a coup. She had Peter III murdered and declared herself Empress.
Therefore, Catherine the Great was related to Peter the Great through her husband, Peter III. However, their relationship was not a direct one, but rather through marriage and a complicated political situation.