Kristoffer Ajer, born on the 17th of April 1998 in Norway, is a 27–year-old defender who primarily plays as a central defender. Currently, he is representing Brentford, where he dons the number 20 jersey. Standing at 1.96m (about 6ft 5in) tall and weighing 84kg (or approximately 13st 3lb), Ajer is a towering figure on the field, having also represented the Norwegian national team. Transfermarkt reports his current market value to be around £13.5m.
In January 2014, Ajer joined Start in the Eliteserien in Norway as a trainee. He debuted in the 2014 season at Start in Norway, where he made 13 first-team appearances and scored one goal in league matches. He continued to perform for Start in the 2015 season, securing 28 first-team appearances and scoring eight goals in league matches. His stint at Start lasted until the 2016 season where he had 11 first-team appearances.
Ajer's football journey took a turn in July 2016 when he transferred from Start in the Eliteserien in Norway to Celtic in the Premiership in Scotland for around £750k. During the seasons of 2017-2018, 2018-2019, 2019-2020, and 2020-2021, Ajer was a regular in Celtic's first team, making a total of 115 appearances and scoring five goals in league matches. His tenacity and exceptional presence in the heart of Celtic's defence were notable during his time with the club.
In the midst of his time at Celtic, Ajer spent a part of the 2016-2017 season on loan at Kilmarnock in the Premiership in Scotland, during which he made 16 first-team appearances.
In July 2021, Ajer transferred from Celtic in the Premiership in Scotland to Brentford in the Premier League in England for a fee of around £14m. He has since been a regular for Brentford during the seasons 2021-2022, 2022-2023, 2023-2024, 2024-2025, and the current season of 2025-2026, making a total of 100 first-team appearances and scoring three goals. Ajer has also featured for Brentford in the League Cup 2025-2026, with three starts. Internationally, he has represented Norway in the World Cup qualifiers Europe 2024-2026, scoring a goal in his eight starts, and in the Nations League 2024-2025 with two starts.
