I mostly watch Korean Dramas so here are my recs
Goblin : Goblins, reapers, reincarnation ect.
A Korean Odyssey: many fantasy related characters
Blade Man: Superhero like man with blades
Blood: Vampires
Black Knight: Reincarnation, and internal life
Bring it On Ghost: Ghosts
Oh my Ghostess: Also ghosts
Come Back Mister: Second chance at life
Secret Garden: Body switching
Surplus Princess: Mermaids
Strong Woman Do Bong Soon: super strength
The Beauty Inside: Changing appearance
The Girl who sees scents: Ability to see traces of different scents
Legend of the Blue Sea: Mermaids
The Master's Sun: Ghosts
Tomorrow with You: Time Travel
W: Jumping between realities
You Who Came from the Stars; Alien