Kingdom

Same genre, mutants, monsters, zombies..... If dark hole is ur cup of tea then kingdom will too. Although kingdom is waaay better than dark hole in my opinion

Both are about zombie apocalypse.
Be sure to watch all parts of Kingdom!!!
This GZ is set on modern times where as Kingdom is set in Joseon times.

Both are historical dramas (Kingdom has fantasy elements, though) with gorgeous cinematography and a unique, rich autumn-like color palette. The ML in both is the only child of the prior king who dies in episode 1 and the queen who was of lower position which threatened/threatens his position. In both he has a childless stepmother who is scheming to have him killed.