Kdramas with a person with a double life, hiding or using one life to achieve something?

 3GGG:

In addition:

• Mother | Mother and Child need to hide their identity in order to save the child from abuse.
• The Crowned Clown | Emperor's body double.
• Black | Grim Reaper hiding in a human's body.
• A Beautiful Mind | ML is a doctor who must hide he's also a psychopath.
• Always | ML used to be a bad person.
• Cruel City | so many people hiding their identities in this one.
• Are You Human Too? | ML must hide that he's an android.
• Goblin | Grim reaper must hide his identity from the woman he falls in love with.
• Hello Monster | Two people hide their identities in this one.
• I’m Not a Robot | FL hides the fact that she's not an android from the ML.
• Let Me Introduce Her | FL hides her identity (when she regains her memories, that is).
• Memories of the Sword | FL's mother hides her identity from her daughter.
• Mulan | FL must hide that she's a woman.

WOW this is a really good list thank you :)