Kristoffer Ajer, born on 17 April 1998 (age 28), is a Norwegian central defender now with Brentford. A commanding 6ft 5in (1.96m), he first made his name at Start, where his 2015 league season was unusually productive for a player of his position: eight goals in 28 appearances.
Celtic moved for him in July 2016, paying Start around £750,000. He arrived young, raw and very clearly built for senior football, but his Celtic years were not just about size. He developed into an important first-team defender, with enough pace and confidence on the ball to make him more than a penalty-box stopper.
In July 2021, Ajer left Celtic for Brentford in a deal worth around £14m. It was a substantial fee and a clean example of Celtic buying early, developing properly, and selling into England at a serious profit – a model the club talks about often enough, though it does not always execute quite so neatly.
At Brentford, Ajer has remained a regular first-team presence into 2026-27. He has made five Premier League appearances this season, along with one in the FA Cup and one in the League Cup, giving him seven appearances in all competitions for the club.
He has also stayed involved with Norway, with eight World Cup qualifying appearances and one goal, plus four Nations League appearances and another goal. His current market value is around £15.5m, according to Transfermarkt.
Ajer’s career has moved in a clear line: early promise at Start, development and first-team responsibility at Celtic, then a move to the Premier League with Brentford. He remains an established defender at club and international level.
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