Does anyone know of any dramas where the main character hides who they really are or lives a double life? The genre doesn't matter :)

Monster 
Mask
Cruel City
Angry mom
Doctor Stranger
Gu Family Book
Legend of the blue sea
Summer's Desire (but that's not the main subject at all and just for a few ep )
You're All Surrounded has someone with a hidden motive who is assigned to a police precinct. 
200 pounds beauty
49 days
angry mom
birth of a beauty
glass mask
heaven's promise
high school - love on
lady & liar
mask (2015)
miss ripley
missing you
myung wol the spy
one well-raised daughter
perfect couple
bride of the century
the princess of wei young
who are you: school 2015
you're beautiful
queen seon duk
empress ki
Eternal Love is my favorite, although the double life plot doesnt stay throughout the whole drama, it is relevant for the plot
Healer
Maou
Tomorrow with you
Joker Yurusarezaru Sousakan
Giragira
Blood (vampire), City Hunter, Pinocchio, You Who Came from the Stars (Alien), Rurouni Kenshin (ex-Assassin) and The liar and his lover 
Love In the Moonlight