Alexander Isak was born on 21 September 1999 and raised in Solna, Stockholm. He came through the youth ranks at local club AIK, making his senior debut in February 2016 at age 16 and quickly becoming the youngest scorer in AIK's Allsvenskan history. His early promise attracted Bundesliga side Borussia Dortmund, who signed him in January 2017 for a reported €9 million — a record fee for an Allsvenskan player at the time. He won the DFB-Pokal with Dortmund in 2016–17 before a productive loan spell at Willem II in the Eredivisie helped him rediscover his form.
Isak moved to Real Sociedad in 2019, where he developed into a consistent La Liga striker. He was part of the squad that won the 2019–20 Copa del Rey and scored the club's first La Liga hat-trick by a Swedish player in over 70 years. In August 2022, Newcastle United signed him for a club-record fee. He went on to score 21 Premier League goals in the 2023–24 season and netted his 50th Premier League goal in February 2025, having also helped Newcastle claim the 2024–25 EFL Cup.
A tall, two-footed centre-forward with sharp movement, composure in front of goal, and effective link-up play, Isak joined Liverpool in September 2025 for a reported £125 million — a British transfer record — where the club will look to him as a primary attacking outlet.
Isak made his senior debut for Sweden in January 2017 and became the country's youngest-ever international goalscorer. He has earned over 50 caps and represented Sweden at UEFA Euro 2020.