Karl Menzies (born 17 June 1977) is an Australian former professional road bicycle racer. He finished second in the 2006 USA Cycling National Racing Calendar to Floyd Landis. Menzies turned professional in 2005, he spent one season on the Advantage Benefits/Endeavour team.

In 2006, he won the Nature Valley Grand Prix, ahead of teammate Greg Henderson. In 2005, he finished first overall at the International Cycling Classic. In 2007, he won stage 1 of the Jacob's Creek Tour Down Under and was the overall winner at the International Tour de Toona stage race.