Koen Casteels (Dutch pronunciation: [ˈkun kɑsˈteːls]; born 25 June 1992) is a Belgian professional footballer who plays as a goalkeeper for Saudi Pro League club Al-Qadsiah and the Belgium national team.

Formed at Genk, Casteels spent most of his professional career in Germany with TSG Hoffenheim, Werder Bremen (loan) and VfL Wolfsburg, making over 200 Bundesliga appearances.

[4] Casteels was signed by VfL Wolfsburg from TSG Hoffenheim in January 2015, but spent the first six months of the three-and-a-half-year contract on loan at Werder Bremen.

[12] Manager Roberto Martínez often chose four goalkeepers in his international selections, and as the 2018 FIFA World Cup only permitted three, Casteels battled with Matz Sels for the final space behind Thibaut Courtois and Simon Mignolet.

[17] Casteels played in all of Belgium's games at UEFA Euro 2024 and impressed, making important saves and also recording an assist in their 2-0 win over Romania.