How to Find the Character ID in Crusader Kings II

In Crusader Kings III (CK3), you can find a character's ID by enabling the debug mode and hovering your mouse over the character.

Enable debug mode

First, you need to enable debug mode. You can find the instructions here.

Hover over the character

Once the debug mode is enabled, character IDs can be seen by hovering the cursor over a character in the game.

Note that this ID is not the Historical ID.