Yıldırım Mert Çetin (born 1 January 1997) is a Turkish professional footballer who plays as a centre-back for Serie A club Hellas Verona, on loan from Roma, and the Turkey national team.
Çetin made his professional debut for Gençlerbirliği in a 2–1 Süper Lig loss to Kayserispor on 19 November 2017.
On 16 August 2019, he joined Italian Serie A club Roma. He was sent on a one-year loan to Hellas Verona on 25 August 2020.
He made his debut for Turkey national team on 17 November 2019 in a Euro 2020 qualifier against Andorra, substituting Merih Demiral in the 80th minute.