Namesakes
Hannes Hafstein
(m) 1861-1922 
Icelandic Presidents and Prime Ministers 1904-1909; 1912-1914 (prime minister)
Hannes Kolehmainen
(m) 1889-1966
Notable Athletes (track)
Olympic Medalists 1912; 1920 10000 m; 5000 m; individual cross country; team cross country; marathon (silver/gold)
Hannes Alfvén
(m) 1908-1995
Nobel Prize Winners 1970 (physics)
Notable Scientists and Inventors
Kaarlo Maaninka
(a.k.a. Hannes) (m) 1953-
Olympic Medalists 1980 10000 m; 5000 m (silver/bronze)
Hannes Þór Halldórsson
(m) 1984-
Notable Athletes (soccer)
Hannes Aigner
(m) 1989-
Olympic Medalists 2012 canoe slalom (bronze)