Population of South Korea : 48,846,823 (July 2006 estimated)
You may see a list of famous Koreans or famous people of Korean descent here:
http://en.wikipedia.org/wiki/List_of_famous_Koreans
Here are some of the famous Koreans:
Ban Ki-moon (반기문), Secretary-General of the United Nations, former Minister for Foreign Affairs
The King Sejong (세종대왕), inventor of Hangul, the natiive Korean alphabet/character
Chun Doo-hwan (전두환) President, 1980-1988
Kim Dae-jung (김대중) President, 1998-2003
Kim Il-sung (김일성) North Korean Communist dictator, 1948-1993
Park Chung-hee (박정희) Military ruler, 1961-1963; President, 1963-1979
Hwang Woo-suk (황우석), biomedical scientist, fabricated his papers on stem cell research
Im Kwon-taek (임권택) , movie director, winner of the Honorary Golden Berlin Bear of Berlin International Film Festival (2005)