Alexei Semenov (Алексей Семёнов) (born April 10, 1981 in Murmansk, USSR) plays defence for the San Jose Sharks in the National Hockey League. He was selected by the Edmonton Oilers in the second round of the 1999 NHL Entry Draft, 36th overall.
In 2001, he was awarded the Max Kaminsky Trophy as the best defenceman in the Ontario Hockey League. After playing three full seasons for the Oilers and their top farm club, the Hamilton Bulldogs, he was traded to the Florida Panthers for a conditional draft pick in the 2006 NHL Entry Draft on November 19, 2005. Upset at his assignment to the Rochester Americans at the start of the 2006-07 season, Semenov left Rochester after four games to play for Ufa Salavat Yulayev in Russia. On July 27,2007. Semenov signed a one-year contract with the San Jose Sharks.
Semenov is known for registering one of the hardest, if not the hardest shot in the NHL, routinely clocking on and above 105 miles per hour.