Kristoffer Vassbakk Köpp Ajer (born 17 April 1998) is a Norwegian professional footballer who plays as centre-back or right-back for Premier League club Brentford and the Norway national team.

As a youth player he originally started his footballing career at Rælingen FK before joining Lillestrøm SK when he was eleven years old.

[5] While playing professionally for IK Start, he attended Kristiansand Katedralskole Gimle (High School) where he was known as a very conscientious and diligent student receiving a total of 18 straight A's.

He attributed this to his strong competitive instinct and self-discipline, as well as the support from his teachers and parents and the fact that he values having a good education outside of his footballing career.

[7] On the reasons why he excelled as a footballer, he attributed this to his early physical development, strength and maturity: I feel like I've been pretty lucky in my career.

On 21 July 2021, Ajer completed a move to Premier League club Brentford on a five-year deal for an undisclosed fee.