Luca Jannis Kilian (born 1 September 1999) is a German professional footballer who plays as a defender for Mainz 05.
Kilian joined the youth academy of Borussia Dortmund at the age of 11 from his local club Hombruch. On 24 May 2019, he signed a professional contract with SC Paderborn 07. He made his professional debut with Paderbon in a 3–2 Bundesliga loss to FC Bayern Munich on 28 September 2019.
On 10 August 2020, Kilian signed for Bundesliga club Mainz 05, on a four-year deal.
Kilian is the grandson of the German former footballer Amand Theis. On 13 March 2020, Kilian tested positive for coronavirus.