Lassi Olavi Ketola (born 16 January 1978) is a Finnish former professional tennis player. Born in Kajaani, Ketola was a five-time winner at the national doubles championships and played collegiate tennis for the UCLA Bruins before turning professional. Ketola made two doubles finals on the ATP Challenger Tour and was a Davis Cup representative for Finland in 2004, partnering Juho Paukku in a doubles rubber against Israel.