O Lamento (2016)

Both of these have a dark vibe and deal with similar themes such as demons, possessions, and exorcisms.

Similar themes of a man and his family being possessed by powerful demons and exorcism.

Both the movies involve Asian shamanism and Asian occult themes. Both movies also involve themes like demonic possession as well as black magic, curses and traditional ritualistic stuff.

Both are supernatural horror films. There is a lot of mystery surrounding them and the feeling and presence of unease is there.

police investigation in a creepy village = folk horror masterpiece .

Both horror films go around a possession case set in a village/rural area, either from Thailand or South Korea. As The Medium's producer, Na Hong Jin's work constitutes a big force of influence, making it obvious its resemblance with The Wailing.

Both horror stories that feature shamanistic rites and supernatural beliefs. One is to cast out a demon from a human body while the other is to prevent (the death of) an unmarried guy from becoming a vengeful ghost.

Both movies revolve around demons, demonic possession, and exorcism.

Both are horror films that tackle religious themes and doctrine. As the main characters delve deeper, they second guess who and what is truly evil.