Kristoffer Ajer, born on 17 April 1998 (age 28), is a towering 6ft 5in (1.96m) Norwegian central defender now with Brentford. He first made his mark at Start, where his 2015 league season – 28 appearances and eight goals – was an early sign that he was not just another big centre-half.
Celtic brought him from Start in July 2016 for around £750,000. His early development included a loan spell that helped turn promise into something more usable, and by the time he settled into the Celtic side he had the scale, stride and confidence to carry the ball out from the back. There were rough edges, naturally. There usually are with young defenders asked to learn in public.
By 2021, Ajer had become an important first-team player at Celtic rather than merely a project. His departure to Brentford in July that year, for around £14m, was a clear profit on the original outlay and one of the cleaner examples of Celtic buying young, developing properly and selling at the right end of the market.
At Brentford, he has continued his career in England as a central defender, with his current market value put at around £15.5m by Transfermarkt. In 2026-27 he has made one Premier League appearance and one FA Cup appearance for Brentford.
He has also remained involved with Norway, making five World Cup appearances and eight European World Cup qualifying appearances this season, scoring once in qualifying. From Start to Celtic and then Brentford, Ajer’s career has followed a fairly clear line: early responsibility, proper development in Glasgow, then the Premier League move his Celtic form had earned.
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