The most championships contested is 12 by 50 kilometre walker Jesus Angel Garcia (ESP). The most by a woman is 11 by another race walker, Susana Feitor (POR). A thorough list of most appearances is given from page 37. The most rounds competed by an athlete at the World Championships is 59 by Merlene Ottey (JAM/SLO) in 1983-1997 and 2003/2007. The most by a man is 44 by sprinter Usain Bolt (JAM) at 100m, 200m and 4x100m relay in 2005-2017. Second on that list is Frankie Fredericks (NAM) with 41 starts across 1991-2003.

The oldest World Champion is Ellina Zvereva (BLR), winner of the 2001 discus throw at 40 years 269 days. The oldest male champion is Yohann Diniz (FRA), winner of the 2017 50 kilometres walk at 39 years 224 days
The youngest gold medallist is Merlene Frazer (JAM) who at 17 years 248 days was part of the winning Jamaican 4x100m relay squad in 1991. The youngest individual champion is Tirunesh Dibaba (ETH), 5000m winner in 2003 at 17 years 333 days. The youngest male champion is Ismael Kirui (KEN), 5000m winner in 1993 at 18 years 177 days.