William Cheruiyot Sigei (born 11 October 1969 in Cheboi'ngong' village, just outside Kapsimotwo village, Bomet, Kenya) is a former Kenyan long-distance runner who won the IAAF World Cross Country Championships in 1993 and 1994. In 1994 he a set a new world record over 10,000 metres in Oslo with 26:52.23 minutes.