Alexander Kristoff (born 5 July 1987) is a Norwegian former road bicycle racer, who last rode for UCI ProTeam Uno-X Mobility and competed professionally from 2006 to 2025.

A sprinter and classics rider, Kristoff is the most successful Norwegian cyclist by number of wins, having taken almost 100 victories during his professional career. He has won four Tour de France stages, the 2014 Milan–San Remo and 2015 Tour of Flanders one-day races – as a result, becoming the only Norwegian rider, as of 2026, to win a cycling monument – and has won medals in the road race at the Olympic Games (2012; bronze), the UCI Road World Championships (2017; silver), and the European Road Cycling Championships (2017; gold). He also holds the record for most wins at the one-day races Eschborn–Frankfurt (four) and the Grand Prix of Aargau Canton (three), and most stage wins at the Tour of Oman (nine), the Tour of Norway (eleven), and the Arctic Race of Norway (seven).

At the age of six, he moved from Oslo to Stavanger. His stepfather got him interested in cycling rather than football. He started riding for Stavanger SK. At 16 he won the Norwegian National Road Race Championships in the youth category, and finished fourth at the European Youth Summer Olympic Festival. He turned professional in 2006 with Glud & Marstrand–Horsens. In 2007, he won the Norwegian National Road Race Championships at 19, beating Thor Hushovd in a sprint of four riders. He won a stage at the Ringerike GP in both 2008 and 2009, and finished second to Kurt Asle Arvesen in the National Road Race Championships in 2009.

Kristoff joined the BMC Racing Team, a UCI Professional Continental team, for the 2010 season. In his first season with the team, his best result was a third-place finish at the Philadelphia International Championship. The following year, he took his first victory with the team, winning the Norwegian National Road Race Championships title for the second time, and entered his first Grand Tour – the Giro d'Italia, finishing third on stage eight.

For the 2012 season, Kristoff joined Team Katusha. His first victory with the team was stage 3a of the Three Days of De Panne, but lost the race lead during the final individual time trial stage; he ultimately won the race's points classification. He again competed in the Giro d'Italia, finishing second to Mark Cavendish on stage thirteen. Having finished third in the Norwegian National Road Race Championships in late June, Kristoff won a bronze medal in the road race at the London Olympics the following month, leading home the main field eight seconds down on race winner Alexander Vinokourov. Following the Olympics, Kristoff won a stage and the points classification at the Danmark Rundt, finished third overall and won the points classification at the World Ports Classic, and finished second behind solo winner Lars Bak at the Grand Prix de Fourmies.

The following year, Kristoff led home the chase group at March's Milan–San Remo, finishing in eighth place for his first top-ten cycling monument result. He again won stage 3a of the Three Days of De Panne, to take the race lead ahead of the final individual time trial stage where he fared better than in 2012, finishing sixth – but dropped behind Sylvain Chavanel in the general classification. He then placed fourth at the Tour of Flanders, again leading home a chasing group of riders, and also finished in the top ten places at Paris–Roubaix with ninth. He then won the opening two stages of Tour of Norway, before winning a third stage on the final day. At June's Tour de Suisse, Kristoff took his first victory at UCI World Tour level, winning the fifth stage into Leuggern from a bunch sprint. After losing out to Thor Hushovd in the Norwegian National Road Race Championships, Kristoff then competed in his first Tour de France, placing second on the opening stage. Following the Tour de France, Kristoff finished fourth overall at the Tour des Fjords, having won an individual stage, the team time trial – as part of Team Katusha – and the points classification. His final notable result of the year was a third-place finish at the Vattenfall Cyclassics in Germany, behind home riders John Degenkolb and André Greipel.

Kristoff took his first win of 2014 at February's Tour of Oman, winning the second stage of the race. The following month, he became the first Norwegian rider to win a cycling monument, when he won Milan–San Remo in a sprint finish of some 25 riders. He again finished in the top five at the Tour of Flanders, with a fifth-place result, before winning the Eschborn–Frankfurt – Rund um den Finanzplatz one-day race in a sprint finish in Frankfurt. The latter result started a prolific month of May for Kristoff, as he won two stages and the points classification at the Tour of Norway, and then went on to win three stages, the general classification and the points classification at the Tour des Fjords.

Having earlier finished second on stages four and six, Kristoff took his first Grand Tour stage win with victory on stage twelve of July's Tour de France, prevailing in Saint-Étienne ahead of Peter Sagan and Arnaud Démare. He took another stage win on stage 15, beating Heinrich Haussler and Sagan in Nîmes, as he ultimately finished as runner-up in the points classification, some 150 points in arrears of Sagan. He then followed this up with second overall at the Arctic Race of Norway, along with two stage wins and the points classification, and a bunch sprint victory at the Vattenfall Cyclassics in Hamburg. He competed in the road race at the UCI Road World Championships for the first time since 2010, culminating in an eighth-place finish. He finished the season with fourteen victories, and an eighth-place finish in the final standings of the UCI World Tour.