Karl Gustaf Lennart Lindroos (December 2, 1886 – July 26, 1921) was a Finnish breaststroke swimmer who competed in the 1912 Summer Olympics. He was born in Helsinki. In 1912 he was eliminated in the semi-finals of the 200 metre breaststroke event as well as in the semi-finals of the 400 metre breaststroke competition.^[1]