Kristof Vliegen (born 22 June 1982 in Maaseik) is a former Belgian tennis player. He plays right-handed and he turned professional in 2001.
He was a semi-finalist in Chennai in 2006 and in May of the same year, he reached the final of the ATP tournament in Munich, setting up the first ever all-Belgian men's singles final against Olivier Rochus. In July, Vliegen reached the second round of Wimbledon.
In Doha, the first tournament of the year he defeated Spaniard Óscar Hernández with 6-1, 6-7 and 6-7. In the next round he faced German Philipp Kohlschreiber. He was defeated in three straight sets 4-6, 7-6 and 6-4. At the Australian open he met Italian Simone Bolelli but lost in three long sets 6-7, 5-7 and 6-7. One week later he started in the SA Tennis Open as the seventh seed. In the first round he won in two straight sets of unranked Ross Hutchins. In the next round he defeated Czech Jan Minář. In the quarterfinals he lost to world number 6 Jo-Wilfried Tsonga in straight sets 4-6 and 1-6. At the Open 13 in Marseille he faced Czech Jan Hernych in the first round but lost in three sets: 6-3, 3-6 and 6-4.