Spoilers for The Great ahead!
1. In The Great, Catherine meets Peter III when he is already Emperor, just before their marriage. In real life, the sequence of events was very different.

2. Peter's aunt Elizabeth was actually Empress for most of Catherine and Peter's marriage – although the real Elizabeth was not quite the character she is in the show.

3. Elizabeth had become Empress after deposing Ivan IV, who was Emperor at the time – and an actual baby.

4. In The Great, Peter III has serious parental issues – especially where his mother is concerned.

5. Peter III became Emperor in 1762, upon the death of his aunt Elizabeth.

6. In The Great, one of Catherine's problems at court is her Germanness, in opposition to Peter's Russianness, but in reality he was also German and alienated his own Russian court.

7. Peter and Catherine's marriage was not a happy one, and both of them had lovers – although not the ones the show depicts.

8. Towards the end of Season 1 of The Great, Catherine reveals she is pregnant and names her unborn baby Paul.

9. The character of Orlo seems to be partially inspired by Grigory Orlov, who was one of Catherine's lovers and who helped her overthrow her husband.

10. Like in The Great, the real Peter discovered the conspiracy to dethrone him, forcing Catherine to enact her plans immediately. With the support of the military, she had Peter arrested and forced him to abdicate, placing herself on the throne.

11. As for Catherine's personality, just as she's depicted in The Great, the real Catherine was passionate about literature, education, and the arts.

12. Catherine was a huge fan of Voltaire, as she is in The Great – although she never met him in real life.

13. In the show, Catherine is vehemently against war, but in reality she was quite militaristic once she became Empress.

14. As in The Great, Catherine really did volunteer herself for a smallpox variolation experiment.

15. Finally, the show is correct in stating that Catherine never had sex with a horse – but the rumor that she did still persists to this day.
