Namesakes
Kaarlo Castrén
(m) 1860-1938 
Finnish Presidents and Prime Ministers 1919 (prime minister)
Kaarlo Maaninka
(m) 1953-
Olympic Medalists 1980 10000 m; 5000 m (silver/bronze)
Kaarlo Juho Ståhlberg
(m) 1865-1952
Finnish Presidents and Prime Ministers 1919-1925 (president)
Kaarlo Tuominen
(m) 1908-2006
Olympic Medalists 1936 3000 m steeplechase (silver)
Kalervo Toivonen
(a.k.a. Kaarlo) (m) 1913-2006
Olympic Medalists 1936 javelin throw (bronze)