Alexander Gennadiyevich Legkov (Russian: Алекса́ндр Геннáдьевич Легков; born 7 May 1983) is a retired Russian cross-country skier who competed internationally between 2002 and 2017. He has five individual World Cup victories including one Tour de Ski title, as well as gold and silver medals at the 2014 Winter Olympics.

Legkov participated in three Winter Olympic Games (2006, 2010, 2014). He finished fourth after a strong final push to catch then-leader Johan Olsson of Sweden at the 2010 Winter Olympics' 30 km double pursuit. Olsson finished in third place with Legkov 1.2 seconds behind. Legkov's next best result was eight in the 4 × 10 km relay at the 2010 Games in Vancouver.

In 2014 Winter Olympics in Sochi Legkov won the gold medal in the 50 km freestyle, and the silver medal in the 4 × 10 km relay.

Legkov was second behind Germany's Tobias Angerer in the 2006–07 World Cup.

He earned a silver in the 4 × 10 km relay and finished twice in sixth place (15 km, 15 km + 15 km double pursuit) at the FIS Nordic World Ski Championship in Sapporo in 2007.

Alexander Legkov was Total winner of Tour de Ski 2012–13 when he defeated Dario Cologna, Maxim Vylegzhanin and Petter Northug racing up Alpe Cermis on 6 January 2013.

On 6 April 2018, Legkov announced his retirement from sport during his participation at the competition "Sports Elite" in Khanty-Mansiysk.

In December 2016, the International Ski Federation provisionally suspended six Russian cross-country skiers linked to doping violations during the 2014 Winter Olympics, including Legkov. In November 2017, Legkov was disqualified for doping offences by the International Olympic Committee, and his 2014 Olympic results were annulled. In February 2018, the international Court of Arbitration for Sport reinstated Legkov's results in Sochi 2014, including two medals, and annulled disqualification imposed by IOC. CAS concluded that there were no sufficient evidence that Legkov had broken anti-doping rules.